Combined Guarantor Subsidiaries - Noncash Investing and Financing Activities - Summary (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Real Estate Investments, Net [Abstract]
Additions to real estate assets accrued but not yet paid	$ 26,572	$ 23,318
Lease liabilities arising from obtaining right-of-use assets	4,042		$ 4,074
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Decrease in real estate assets	(60,059)	0
Decrease in mortgage and other indebtedness	124,111	0
Decrease in operating assets and liabilities	9,333	0
Decrease in intangible lease and other assets	(1,663)	0
Guarantor Subsidiaries
Real Estate Investments, Net [Abstract]
Additions to real estate assets accrued but not yet paid	10,423	5,604
Distribution of properties to owners	11,455	0
Lease liabilities arising from obtaining right-of-use assets	489	0	$ 490
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Decrease in real estate assets	(60,058)	0
Decrease in mortgage and other indebtedness	115,271	0
Decrease in operating assets and liabilities	8,246	0
Decrease in intangible lease and other assets	$ (1,663)	$ 0