Earnings Per Share - Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerators:
Net income	$ 16,375	$ 12,074	$ 30,195	$ 21,641
Denominators:
Basic weighted average common shares outstanding (in shares)	33,621,444	33,417,079	33,500,736	33,327,169
Dilutive effect of share based awards (in shares)	888,956	790,894	930,292	803,303
Diluted weighted average common shares outstanding (in shares)	34,510,400	34,207,973	34,431,028	34,130,472
Earnings per share:
Basic (in dollars per share)	$ 0.49	$ 0.36	$ 0.90	$ 0.65
Diluted (in dollars per share)	$ 0.47	$ 0.35	$ 0.88	$ 0.63
Weighted average common shares considered anti-dilutive in computing diluted earnings per share (in shares)	59,455	62,084	130,103	116,922