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Earnings Per Share - Reconciliation of Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator
Income (loss) from continuing operations - basic and diluted	$ 10,569	$ 3,644	$ 10,846	$ 7,222	$ 7,917	$ 2,653	$ 1,632	$ (983)	$ 32,281	$ 11,219	$ (40,712)
Denominator
Weighted average common shares outstanding - basic (in shares)									89,996	85,421	83,697
Dilutive effect of stock options and restricted stock awards (in shares)									2,385	2,554	0
Weighted average common shares outstanding - diluted (in shares)									92,925	87,975	83,697
Basic (in shares)	$ 0.12	$ 0.04	$ 0.12	$ 0.08	$ 0.09	$ 0.03	$ 0.02	$ (0.01)	$ 0.36	$ 0.13	$ (0.49)
Diluted (in shares)	$ 0.11	$ 0.04	$ 0.12	$ 0.08	$ 0.09	$ 0.03	$ 0.02	$ (0.01)	$ 0.35	$ 0.13	$ (0.49)
Convertible debt [Member] \| Convertible Notes due 2021 [Member]
Denominator
Dilutive effect of the convertible notes (in shares)									544	0	0