Summary of Operations and Significant Accounting Policies - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings (numerator)
Net income attributable to common stockholders	$ (4,773)	$ 2,837	$ 15,078	$ 11,132	$ 16,665	$ 19,427	$ 17,385	$ 10,202	$ 24,274	$ 63,678	$ 26,532
Shares (denominator)
Weighted average common shares outstanding (basic)									48,210	47,184	46,363
Dilutive effect of stock options and stock awards outstanding									1,290	1,410	1,295
Adjusted weighted average common shares outstanding (diluted)									49,500	48,594	47,658
Earnings per share attributable to common stockholders
Basic	$ (0.10)	$ 0.06	$ 0.31	$ 0.23	$ 0.35	$ 0.41	$ 0.37	$ 0.22	$ 0.50	$ 1.35	$ 0.57
Diluted	$ (0.10)	$ 0.06	$ 0.31	$ 0.23	$ 0.34	$ 0.40	$ 0.36	$ 0.21	$ 0.49	$ 1.31	$ 0.56