Common Stock and Share-Based Compensation - Share-Based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ (501)	$ 620	$ 3,230	$ 7,245
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	(100)	1,190	1,984	3,735
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	(1,066)	(1,215)	(287)	(68)
Phantom shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 665	$ 645	$ 1,533	$ 3,578