Earnings Per Share - Components of Numerator and Denominator for Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net (loss) income attributable to common shareholders - Basic									$ (57,713)	$ (16,951)	$ 37,513
Interest on Convertible Notes									0	0	694
Gain on derivatives									0	0	1,581
Net (loss) income attributable to common shareholders - Diluted									$ (57,713)	$ (16,951)	$ 36,626
Denominator:
Weighted average common shares - Basic (shares)									35,815	35,657	35,018
Effective of diluted shares:
Share-based awards (shares)									0	0	425
Convertible Notes (shares)									0	0	723
Weighted average common shares - Diluted (shares)									35,815	35,657	36,166
Net (loss) income per share attributable to common shareholders - Basic (usd per share)	$ (0.03)	$ (0.09)	$ (1.44)	$ (0.05)	$ (0.55)	$ (0.01)	$ 0.04	$ 0.05	$ (1.61)	$ (0.48)	$ 1.07
Net (loss) income per share attributable to common shareholders - Diluted (usd per share)	$ (0.03)	$ (0.09)	$ (1.44)	$ (0.05)	$ (0.55)	$ (0.01)	$ 0.04	$ 0.05	$ (1.61)	$ (0.48)	$ 1.01