Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Details)

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Stockholders' Equity (Details) - USD ($)
3 Months Ended 6 Months Ended
Apr. 28, 2017
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
May 06, 2014
Class of Stock [Line Items]            
Authorized amount of common stock repurchase           $ 50,000,000
Common Stock            
Class of Stock [Line Items]            
Authorized amount of common stock repurchase $ 50,000,000          
Repurchase period (in years) 1 year          
Number of shares repurchased (in shares)   0 235,154 0 1,012,823  
Weighted-average cost per share (in dollars per share)   $ 0.00 $ 21.71 $ 0.00 $ 20.98  
Total cost of shares repurchased   $ 0 $ 5,106,000 $ 0 $ 21,244,000