Summary of Significant Accounting Policies - Deferred Costs and Other Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred costs and other assets
Deferred lease costs, net	$ 209,277	$ 249,010
In-place lease intangibles, net	31,417	65,825
Acquired above market lease intangibles, net	44,337	64,813
Marketable securities of our captive insurance companies	52,760	40,099
Goodwill	20,098	20,098
Other marketable and non-marketable securities	363,554	253,732
Prepaids, notes receivable and other assets, net	492,582	516,463
Deferred costs and other assets	1,214,025	1,210,040
Deferred Lease Costs
Deferred lease costs	443,313	497,570
Accumulated amortization	(234,036)	(248,560)
Deferred lease costs, net	209,277	249,010
Amortization, included in statements of operations and comprehensive income
Amortization of deferred leasing costs		$ 56,646	$ 54,323
Amortization of deferred leasing costs	$ 57,201