Net Income 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
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income	$ 136	$ 18,806	$ 18,939	$ 53,572
Weighted average number of common shares outstanding (for basic calculation)	19,984	16,200	19,433	16,113
Dilutive securities	1,122	1,086	1,170	987
Diluted (in shares)	21,106	17,286	20,603	17,100
EPS - basic	$ 0.01	$ 1.16	$ 0.97	$ 3.32
Diluted (In dollars per share)	$ 0.01	$ 1.09	$ 0.92	$ 3.13