Annual report pursuant to Section 13 and 15(d)

Retirement Savings Plans (Narrative) (Details)

v3.6.0.2
Retirement Savings Plans (Narrative) (Details) - USD ($)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]      
Liability to participants under deferred compensation plan $ 8,411,000 $ 6,887,000  
Current liability to participants under deferred compensation plan 472,000 629,000  
401(k) Profit-Sharing Plan [Member]      
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]      
Company contributions to the plan 7,754,000 6,981,000 $ 7,056,000
Deferred Compensation Plan [Member]      
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]      
Company contributions to the plan 200,000 180,000 $ 239,000
Other Noncurrent Assets [Member] | Deferred Compensation Plan [Member]      
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]      
Fair value of mutual fund investments 8,411,000 6,887,000  
Short-term Investments [Member] | Deferred Compensation Plan [Member]      
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]      
Fair value of mutual fund investments $ 472,000 $ 629,000