Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator
Income (loss) from continuing operations - basic	$ 7,917	$ 2,653	$ 1,632	$ (983)	$ (57)	$ (13,451)	$ (13,904)	$ (13,300)	$ 11,219	$ (40,712)	$ (90,828)
Assumed conversions of 2017 Convertible Notes									0	0	0
Adjusted income (loss) from continuing operations - diluted									$ 11,219	$ (40,712)	$ (90,828)
Denominator
Basic - weighted average common shares outstanding (in shares)									85,421	83,697	82,722
Dilutive effect of stock options and restricted stock awards (in shares)									2,554	0	0
Diluted weighted average number of common shares outstanding (in shares)									87,975	83,697	82,722
Income (loss) from continuing operations, basic (in dollars per share)	$ 0.09	$ 0.03	$ 0.02	$ (0.01)	$ 0.00	$ (0.16)	$ (0.17)	$ (0.16)	$ 0.13	$ (0.49)	$ (1.10)
Income (loss) from continuing operations, diluted (in dollars per share)	$ 0.09	$ 0.03	$ 0.02	$ (0.01)	$ 0.00	$ (0.16)	$ (0.17)	$ (0.16)	$ 0.13	$ (0.49)	$ (1.10)
Convertible Notes due 2017 [Member] | Convertible debt [Member]
Denominator
Dilutive effect of the convertible notes (in shares)									0	0	0
Convertible Notes due 2021 [Member] | Convertible debt [Member]
Denominator
Dilutive effect of the convertible notes (in shares)									0	0	0