Combined Guarantor Subsidiiaries - Combined Statements of Cash Flows - Summary (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018		Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss		$ (46,809)	$ (661)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization		69,792	71,750
Net amortization of deferred financing costs, debt premiums and discounts		2,304	1,709
Net amortization of intangible lease assets and liabilities		(551)	(475)
Gain on sales of real estate assets		(228)	(4,371)
Loss on insurance proceeds		(690)	0
Loss on impairment		24,825	18,061
Gain on extinguishment of debt		(71,722)	0
Change in estimate of uncollectable rental revenues		1,540	2,041
Changes in:
Tenant and other receivables		(387)	1,826
Other assets		(3,826)	(2,339)
Accounts payable and accrued liabilities		76,771	8,635
Net cash provided by operating activities		55,488	98,227
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to real estate assets		(26,429)	(39,997)
Proceeds from sales of real estate assets		35,260	11,848
Proceeds from insurance		548	0
Payments received on mortgage and other notes receivable		266	267
Changes in other assets		(321)	(2,277)
Net cash provided by (used in) investing activities		13,737	(28,532)
CASH FLOWS FROM FINANCING ACTIVITIES:
Principal payments on mortgage and other indebtedness		(978,006)	(123,634)
Net cash used in financing activities		(81,321)	(79,332)
NET CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH		(12,096)	(9,637)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, beginning of period		57,512	68,172	$ 68,172
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, end of period		45,416	58,535	57,512
Reconciliation from condensed consolidated statements of cash flows to condensed consolidated balance sheets:
Cash and cash equivalents		21,055	23,346	25,138	[1]
Restricted cash
Restricted cash	[2]					$ 79		$ 3,212
Mortgage escrows	[2]					24,282		31,977
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, end of period		57,512	68,172	68,172		45,416	$ 57,512	58,535
SUPPLEMENTAL INFORMATION:
Cash paid for interest, net of amounts capitalized		35,659	34,896
Guarantor Subsidiaries
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss		62,109	29,615
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization		24,101	24,499
Net amortization of deferred financing costs, debt premiums and discounts		62	(122)
Net amortization of intangible lease assets and liabilities		(611)	(568)
Gain on sales of real estate assets		0	(1,718)
Loss on insurance proceeds		64	0
Loss on impairment		22,770	0
Gain on extinguishment of debt		(61,796)	0
Change in estimate of uncollectable rental revenues		584	476
Changes in:
Tenant and other receivables		(367)	(844)
Other assets		(632)	(883)
Accounts payable and accrued liabilities		(10,251)	(3,016)
Net cash provided by operating activities		36,033	47,439
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to real estate assets		(6,207)	(13,032)
Proceeds from sales of real estate assets		0	2,547
Proceeds from insurance		367	0
Payments received on mortgage and other notes receivable		17	4,457
Changes in other assets		(313)	(142)
Net cash provided by (used in) investing activities		(6,136)	(6,170)
CASH FLOWS FROM FINANCING ACTIVITIES:
Principal payments on mortgage and other indebtedness		(6,709)	(39,516)
Distributions to owners		(41,658)	(56,447)
Contributions from owners		17,363	50,514
Net cash used in financing activities		(31,004)	(45,449)
NET CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH		(1,107)	(4,180)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, beginning of period		13,020	14,544	14,544
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, end of period		11,913	10,364	13,020
Reconciliation from condensed consolidated statements of cash flows to condensed consolidated balance sheets:
Cash and cash equivalents		8,057	5,085	5,880
Restricted cash
Restricted cash						0		2,309
Mortgage escrows						3,856	7,139	2,970
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, end of period		13,020	14,544	$ 14,544		$ 11,913	$ 13,020	$ 10,364
SUPPLEMENTAL INFORMATION:
Cash paid for interest, net of amounts capitalized		$ 3,375	$ 4,217

[1] As of March 31, 2019, includes $609,856 of assets related to consolidated variable interest entities that can be used only to settle obligations of the consolidated variable interest entities and $406,466 of liabilities of consolidated variable interest entities for which creditors do not have recourse to the general credit of the Company. See Note 7.

[2] Included in intangible lease assets and other assets in the condensed consolidated balance sheets.