Variable Interest Entities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Assets:
Net real estate investments	$ 28,348,107			$ 31,119,271
Cash and cash equivalents	1,603,740			284,917
Receivables and other assets	813,047			757,748
Total Assets	32,541,597			33,380,751
Liabilities and equity:
Secured debt	2,459,659			2,990,962
Lease liabilities	427,842			473,693
Total equity	16,961,102	$ 16,936,527	$ 17,066,337	16,506,627	$ 16,225,729	$ 15,969,572	$ 16,047,831	$ 15,586,599
Total liabilities and equity	32,541,597			33,380,751
VIE, Primary Beneficiary
Assets:
Net real estate investments	456,006			960,093
Cash and cash equivalents	22,958			27,522
Receivables and other assets	13,169			14,586
Total Assets	492,133			1,002,201
Liabilities and equity:
Secured debt	166,122			460,117
Lease liabilities	1,325			1,326
Accrued expenses and other liabilities	18,910			22,215
Total equity	305,776			518,543
Total liabilities and equity	$ 492,133			$ 1,002,201