Quarterly report pursuant to Section 13 or 15(d)

Shareholders' Equity (Narrative) (Details)

v3.8.0.1
Shareholders' Equity (Narrative) (Details) - USD ($)
$ / shares in Units, $ in Thousands
 9 Months Ended 12 Months Ended
Sep. 22, 2017
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Dec. 15, 2017
Jan. 27, 2015
Share Repurchase Program [Line Items]            
Share repurchased and retired (in shares)     357,000      
Value of shares repurchased and retired     $ 16,600      
Outstanding common stock acquired, average price (in dollars per share)     $ 46.45      
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased (in shares)   2,700,000        
Common Stock, Dividends, Per Share, Cash Paid (in dollars per share) $ 0.35          
Dividends, Common Stock, Cash $ 18,300 $ 55,013   $ 73,151    
Dividends Payable, Amount Per Share (in dollars per share)         $ 0.35  
4 Million Share Program Approved 1/27/2015 [Member]            
Share Repurchase Program [Line Items]            
Stock Repurchase Program, Number of Shares Authorized to be Repurchased (in shares)           4,000,000
Subsequent Event [Member]            
Share Repurchase Program [Line Items]            
Dividends Payable, Amount Per Share (in dollars per share)         $ 0.35