Annual report pursuant to Section 13 and 15(d)

Net Income Per Common Share (Details)

v3.8.0.1
Net Income Per Common Share (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Apr. 30, 2015
Earnings Per Share [Abstract]        
Net Income (Loss) Available to Common Stockholders, Basic $ 23,578 $ 55,086 $ 47,241  
Net income allocated to common stockholders (in dollars per share) $ 2.10 $ 4.84 $ 3.84  
Weighted Average Number of Shares Outstanding, Basic 11,251,000 11,382,000 12,302,000  
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants     21,000  
Class of Warrant or Right, Number of Securities Called by Warrants or Rights       88,097
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount 2,232 345    
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements 16,000 25,000 49,000  
Net Income (Loss) Available to Common Stockholders, Diluted $ 23,578 $ 55,086 $ 47,241  
Weighted Average Number of Shares Outstanding, Diluted 11,267,000 11,407,000 12,372,000  
Net income allocated to common stockholders plus assumed conversions (in dollars per share) $ 2.09 $ 4.83 $ 3.82