Earnings per Share - Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share, Basic and Diluted [Abstract]
Net income	$ 11,196	$ 58	$ 33,830	$ 12,587
Net income allocated to unvested restricted stock	(96)	0	(330)	(102)
Net income allocated to common shares	$ 11,100	$ 58	$ 33,500	$ 12,485
Denominator for basic earnings per share—weighted-average shares outstanding	26,437	26,274	26,388	21,720
Effect of dilutive securities—employee stock options	105	67	102	41
Denominator for diluted earnings per share—adjusted weighted-average shares outstanding	26,542	26,341	26,490	21,761
Basic earnings per share	$ 0.42	$ 0.00	$ 1.27	$ 0.58
Diluted earnings per share	$ 0.42	$ 0.00	$ 1.27	$ 0.57
Average anti-dilutive options excluded from computation of diluted earnings per share	185	201	166	550