Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measures (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details)

v2.4.0.8
Fair Value Measures (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $)
In Thousands, unless otherwise specified
 9 Months Ended
Sep. 30, 2013
Dec. 31, 2012
Sep. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value $ 242,230 $ 184,139 $ 32,475
Total liabilities measured at fair value 599 1,322 2,220
Investments, remaining maturity, minimum 3 months    
Investments, remaining maturity, maximum 2 years    
Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 183,293 99,972 27,595
Total liabilities measured at fair value 0   0
Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 58,937 84,167 4,880
Total liabilities measured at fair value 599 1,322 2,220
Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0   0
Total liabilities measured at fair value 0   0
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total liabilities measured at fair value 599 1,322 2,220
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total liabilities measured at fair value 0   0
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total liabilities measured at fair value 599 1,322 2,220
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total liabilities measured at fair value 0   0
Cash Equivalents [Member] | Money Market Funds [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 153,382 70,857 13,700
Cash Equivalents [Member] | Money Market Funds [Member] | Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 153,382 70,857 13,700
Cash Equivalents [Member] | Money Market Funds [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0   0
Cash Equivalents [Member] | Money Market Funds [Member] | Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0   0
Cash Equivalents [Member] | Time Deposits [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 25,092 25,035 10,016
Cash Equivalents [Member] | Time Deposits [Member] | Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 25,092 25,035 10,016
Cash Equivalents [Member] | Time Deposits [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0    
Cash Equivalents [Member] | Time Deposits [Member] | Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0    
Cash Equivalents [Member] | Certificates of Deposit [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value   2,450  
Cash Equivalents [Member] | Certificates of Deposit [Member] | Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value   0  
Cash Equivalents [Member] | Certificates of Deposit [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value   2,450  
Cash Equivalents [Member] | Certificates of Deposit [Member] | Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value   0  
Cash Equivalents [Member] | Repurchase Agreements [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 25,000 25,000  
Cash Equivalents [Member] | Repurchase Agreements [Member] | Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0 0  
Cash Equivalents [Member] | Repurchase Agreements [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 25,000 25,000  
Cash Equivalents [Member] | Repurchase Agreements [Member] | Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0    
Cash Equivalents [Member] | U.S. Government-Backed Municipal Bonds [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 3,218 5,348  
Cash Equivalents [Member] | U.S. Government-Backed Municipal Bonds [Member] | Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0    
Cash Equivalents [Member] | U.S. Government-Backed Municipal Bonds [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 3,218 5,348  
Cash Equivalents [Member] | U.S. Government-Backed Municipal Bonds [Member] | Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0    
Available-For-Sale Short-Term Investments [Member] | Time Deposits [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value     2,128 [1]
Available-For-Sale Short-Term Investments [Member] | Time Deposits [Member] | Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value     0 [1]
Available-For-Sale Short-Term Investments [Member] | Time Deposits [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value     2,128 [1]
Available-For-Sale Short-Term Investments [Member] | Time Deposits [Member] | Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value     0 [1]
Available-For-Sale Short-Term Investments [Member] | Certificates of Deposit [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 1,470 [1] 7,596 [1]  
Available-For-Sale Short-Term Investments [Member] | Certificates of Deposit [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 1,470 [1] 7,596 [1]  
Available-For-Sale Short-Term Investments [Member] | Variable Rate Demand Obligation [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 27,320 [1] 22,640 [1]  
Available-For-Sale Short-Term Investments [Member] | Variable Rate Demand Obligation [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 27,320 [1] 22,640 [1]  
Available-For-Sale Short-Term Investments [Member] | U.S. Government-Backed Municipal Bonds [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value   14,425 [1]  
Available-For-Sale Short-Term Investments [Member] | U.S. Government-Backed Municipal Bonds [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value   14,425 [1]  
Trading Securities [Member] | Mutual Fund Shares [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 259    
Trading Securities [Member] | Mutual Fund Shares [Member] | Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 259    
Trading Securities [Member] | Mutual Fund Shares [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0    
Trading Securities [Member] | Mutual Fund Shares [Member] | Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0    
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 1,929 6,219 2,752
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0   0
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 1,929 6,219 2,752
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0   0
Non Current Assets [Member] | Derivative Financial Instruments, Assets [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value   489  
Non Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value   489  
Non Current Assets [Member] | Mutual Fund Shares [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 4,560 4,080 3,879
Non Current Assets [Member] | Mutual Fund Shares [Member] | Level 1 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 4,560 4,080 3,879
Non Current Assets [Member] | Mutual Fund Shares [Member] | Level 2 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value 0   0
Non Current Assets [Member] | Mutual Fund Shares [Member] | Level 3 [Member]
      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Total assets measured at fair value $ 0   $ 0
[1] Investments have remaining maturities greater than three months but less than two years and are available for use in current operations.