Operating Segments - Profit by Reportable Segment to Net Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total profit from segments	$ 3,938	$ (2,303)	$ 1,491	$ (3,238)	$ (731)	$ (578)	$ (1,013)	$ 1,932	$ (112)	$ (390)	$ 42,878
Depreciation and amortization									(18,579)	(15,588)	(30,658)
General and administrative									(10,614)	(11,089)	(12,708)
Advisory Fee									(9,409)	(9,216)	(12,106)
Other income									7,117	12,757	36,005
Interest Income									23,098	25,955	21,645
Interest Expense									(35,004)	(39,860)	(66,063)
(Loss) gain on foreign currency transactions									(13,378)	(15,108)	12,399
Loss on extinguishment of debt									0	(5,219)	0
Equity in (loss) income from unconsolidated joint ventures									(379)	(2,313)	1,513
Gain on sale or write-down of assets									36,895	15,192	171,530
Income tax provision									147	0	(1,210)
Net income (loss)									11,267	(21,743)	182,692
Operating Segments
Segment Reporting Information [Line Items]
Total profit from segments									27,549	20,537	54,357
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Depreciation and amortization									(14,755)	(13,379)	(22,670)
General and administrative									(10,614)	(11,089)	(12,708)
Advisory Fee									(9,409)	(9,216)	(12,106)
Other income									7,117	12,757	36,005
Interest Income									23,098	25,955	21,645
Interest Expense									(35,004)	(39,860)	(66,063)
(Loss) gain on foreign currency transactions									(13,378)	(15,108)	12,399
Loss on extinguishment of debt									0	(5,219)	0
Equity in (loss) income from unconsolidated joint ventures									(379)	(2,313)	1,513
Gain on sale or write-down of assets									36,895	15,192	171,530
Income tax provision									$ 147	$ 0	$ (1,210)