Assets Held for Sale (Details) - USD ($) $ in Thousands		6 Months Ended
	Feb. 28, 2019	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gains on sale of real estate	$ 33,100
Proceeds from sale of real estate	$ 163,600	$ (168,342)	$ (419,557)
Total other assets held for sale, net		0		$ 20,791
Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total real estate assets held for sale, net		0		110,552
Straight-line rent receivables		0		10,756
Prepaid expenses and other assets		0		430
Deferred lease costs, less accumulated amortization of $0 and $2,446 as of June 30, 2019 and December 31, 2018, respectively		0		9,605
Total other assets held for sale, net		0		20,791
Accumulated amortization on deferred lease costs		0		2,446
Disposal Group, Held-for-sale, Not Discontinued Operations | Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:		0		30,562
Disposal Group, Held-for-sale, Not Discontinued Operations | Building and building improvements
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:		0		77,936
Accumulated depreciation (building improvements)		0		48,453
Disposal Group, Held-for-sale, Not Discontinued Operations | Construction in progress
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:		$ 0		$ 2,054