Quarterly report pursuant to Section 13 or 15(d)

Significant Accounting Policies (Narrative) (Details)

v3.10.0.1
Significant Accounting Policies (Narrative) (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2018
Dec. 31, 2017
Accounting Policies [Abstract]      
Stock Repurchased and Retired During Period, Shares 205,354 327,341  
Stock Repurchase Program, Remaining Authorized Repurchase Amount $ 247,600 $ 247,600  
Stock Repurchased and Retired During Period, Value 30,100 47,400  
Debt and Capital Lease Obligations 45,000 45,000 $ 95,000
Stock Repurchase Program, Authorized Amount 250,000 250,000  
Long-term Debt, Fair Value $ 45,800 $ 45,800 $ 97,100