Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Details)

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Stockholders' Equity (Details) - USD ($)
12 Months Ended
Apr. 26, 2016
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
May 06, 2015
Class of Stock [Line Items]          
Stock repurchase program, extension of period in force 1 year        
Common Stock          
Class of Stock [Line Items]          
Amount authorized to be repurchased $ 50,000,000.0       $ 50,000,000.0
Stock repurchased and retired during period (in shares)   1,012,823 1,798,199 966,595  
Weighted average cost per share (in dollars per share)   $ 20.98 $ 19.51 $ 16.06  
Stock repurchased during period   $ 21,244,000 $ 35,083,000 $ 15,521,000