Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation (Summary of Restricted Stock Unit Activity) (Details)

v2.4.0.6
Stock-Based Compensation (Summary of Restricted Stock Unit Activity) (Details) (Restricted Stock Units (RSUs) [Member], USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Restricted Stock Units (RSUs) [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock units outstanding, beginning, number of shares 296,752 328,795 286,520
Granted, number of shares 185,303 145,768 128,525
Vested, number of shares (91,383) (146,951) (62,417)
Forfeited, number of shares (70,114) (30,860) (23,833)
Restricted stock units outstanding, ending, number of shares 320,558 296,752 328,795
Restricted stock units outstanding, beginning, weighted average grate date fair value per share $ 47.19 $ 37.63 $ 36.35
Granted, weighted average grant date fair value per share $ 46.57 $ 58.37 $ 43.95
Vested, weighted average grant date fair value $ 42.39 $ 38.01 $ 42.95
Forfeited, weighted average grant date fair value $ 46.26 $ 41.79 $ 42.44
Restricted stock units outstanding, ending, weighted average grate date fair value per share $ 48.31 $ 47.19 $ 37.63