Co-investments - Combined Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Equity Method Investment, Summarized Financial Information, Assets [Abstract] (Deprecated 2020-01-31)
Rental properties and real estate under development	$ 404,496		$ 386,047
Total assets	12,790,204		12,936,177
Debt	6,542,951		6,720,746
Other liabilities	36,694		39,140
Equity	6,210,931	$ 6,417,949	6,183,192	$ 6,403,504
Total liabilities and equity	12,790,204		12,936,177
Equity Method Investment, Summarized Financial Information [Abstract]
Property revenues	355,125	392,367
Interest expense	(51,649)	(55,147)
General and administrative	(9,812)	(13,982)
Net income	176,949	328,765
Total co-investment | Affiliated Entity
Equity Method Investment, Summarized Financial Information [Abstract]
Company's share of net income	2,300	2,100
Equity Method Investment, Nonconsolidated Investee or Group of Investees | Total co-investment
Equity Method Investment, Summarized Financial Information, Assets [Abstract] (Deprecated 2020-01-31)
Rental properties and real estate under development	4,054,459		4,242,611
Other assets	224,288		200,777
Total assets	4,278,747		4,443,388
Debt	2,496,205		2,611,365
Other liabilities	189,046		189,515
Equity	1,593,496		1,642,508
Total liabilities and equity	4,278,747		4,443,388
Company's share of equity	962,625		$ 1,018,010
Equity Method Investment, Summarized Financial Information [Abstract]
Property revenues	71,759	77,369
Property operating expenses	(27,331)	(25,715)
Net operating income	44,428	51,654
Interest expense	(16,700)	(20,853)
General and administrative	(4,281)	(4,083)
Depreciation and amortization	(32,709)	(28,437)
Net income	(9,262)	(1,719)
Company's share of net income	$ 17,011	$ 21,297