Dispositions of Real Estate and Discontinued Operations - Assets and Liabilities for Discontinued Operations (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Real estate:
Intangible assets, net	$ 25,000	$ 82,000
Total assets of discontinued operations, net	2,626,306	3,648,265
LIABILITIES
Total liabilities of discontinued operations, net	415,737	403,688
Allowance for doubtful accounts receivable	5,873	4,178
Goodwill	18,000	17,000
Held-for-sale
Real estate:
Buildings and improvements	2,553,254	3,626,665
Development costs and construction in progress	21,509	38,728
Land	355,803	467,956
Accumulated depreciation and amortization	(615,708)	(861,557)
Net real estate	2,314,858	3,271,792
Investments in and advances to unconsolidated joint ventures	5,842	51,134
Accounts receivable, net of allowance of $5,873 and $4,178	20,500	14,575
Cash and cash equivalents	53,085	63,834
Restricted cash	17,168	27,040
Intangible assets, net	24,541	82,071
Right-of-use asset, net	4,109	5,701
Other assets, net(1)	103,965	125,502
Total assets of discontinued operations, net	2,544,068	3,641,649
Total medical office assets held for sale, net	82,238	6,616
Assets held for sale and discontinued operations, net	2,626,306	3,648,265
LIABILITIES
Mortgage debt	318,876	296,879
Lease liability	3,189	4,871
Accounts payable, accrued liabilities, and other liabilities	79,411	83,392
Deferred revenue	11,442	18,520
Total liabilities of discontinued operations, net	412,918	403,662
Total liabilities related to medical office assets held for sale, net	2,819	26
Liabilities related to assets held for sale and discontinued operations, net	415,737	403,688
Goodwill	29,000	30,000
Net Real Estate Assets	$ 73,000	$ 7,000