Income Taxes - Reconciliation of Statutory Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Expected tax at statutory rate	$ 111,760	$ 97,110	$ 95,828
Non-taxable REIT income	(94,270)	(82,717)	(83,022)
State and local tax expense - net of federal benefit	3,075	2,837	2,385
Change in valuation allowance	(363)	(207)	(1,052)
Tax credits/true-up	(5,745)	(3,663)	(6,016)
Miscellaneous	(647)	(2,052)	1,121
Total provision	$ 13,810	$ 11,308	$ 9,244
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Expected tax at statutory rate	21.00%	21.00%	21.00%
Non-taxable REIT income	(17.70%)	(17.90%)	(18.20%)
State and local tax expense - net of federal benefit	0.60%	0.60%	0.50%
Change in valuation allowance	(0.10%)	0.00%	(0.20%)
Tax credits/true-up	(1.10%)	(0.80%)	(1.30%)
Miscellaneous	(0.10%)	(0.40%)	0.20%
Total provision	2.60%	2.50%	2.00%