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, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings (numerator)
Net income attributable to common stockholders	$ 1,268	$ 10,648	$ 5,752	$ (1,733)	$ (4,773)	$ 2,837	$ 15,078	$ 11,132	$ 15,935	$ 24,274	$ 63,678
Shares (denominator)
Weighted average common shares outstanding (basic)									48,597	48,210	47,184
Dilutive effect of stock options and stock awards outstanding									1,192	1,290	1,410
Adjusted weighted average common shares outstanding (diluted)									49,789	49,500	48,594
Earnings per share attributable to common stockholders
Basic	$ 0.07	$ 0.22	$ 0.12	$ (0.04)	$ (0.10)	$ 0.06	$ 0.31	$ 0.23	$ 0.33	$ 0.50	$ 1.35
Diluted	$ 0.07	$ 0.21	$ 0.12	$ (0.04)	$ (0.10)	$ 0.06	$ 0.31	$ 0.23	$ 0.32	$ 0.49	$ 1.31