Summary of Significant Accounting Policies (Details 4) - USD ($) $ / shares in Units, $ 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	May 20, 2015	Dec. 16, 2014
Basic earnings (loss) per share computation:
Net income (loss) attributable to common stockholders —basic	$ (5,431)	$ (2,703)	$ (2,901)	$ (950)	$ (6,375)	$ (2,888)	$ 9,376	$ 6,555	$ (11,985)	$ 6,668	$ 5,251
Weighted average common shares —basic (in shares)									53,078,158	52,872,814	49,817,721
Basic net income (loss) per share (in dollars per share)	$ (0.11)	$ (0.05)	$ (0.05)	$ (0.02)	$ (0.12)	$ (0.05)	$ 0.18	$ 0.12	$ (0.23)	$ 0.13	$ 0.11
Dilutive earnings (loss) per share computation:
Net income (loss) attributable to common stockholders —basic	$ (5,431)	$ (2,703)	$ (2,901)	$ (950)	$ (6,375)	$ (2,888)	$ 9,376	$ 6,555	$ (11,985)	$ 6,668	$ 5,251
Interest expense related to convertible 3.75% senior notes									0	5,391	224
Amortization of discount related to convertible 3.75% senior notes									0	6,680	0
Change in the fair value of derivative									0	(23,144)	0
Net income (loss) attributable to common stockholders —diluted									$ (11,985)	$ (4,405)	$ 5,475
Share Computation:
Weighted average common shares —basic (in shares)									53,078,158	52,872,814	49,817,721
Effect of convertible 3.75% senior notes (in shares)									0	12,732,168	12,732,168
Effect of dilutive stock options and warrants (in shares)									0	1,507,013	1,657,301
Weighted average common shares outstanding —diluted (in shares)									53,078,158	67,111,995	64,207,190
Diluted earnings (loss) per share (in dollars per share)	$ (0.11)	$ (0.05)	$ (0.05)	$ (0.02)	$ (0.12)	$ (0.05)	$ (0.03)	$ 0.01	$ (0.23)	$ (0.07)	$ 0.09
Convertible debt
Share Computation:
Stated interest rate	3.75%								3.75%		3.75%	3.75%	3.75%