Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
REIT distribution requirement (as a percent)	90.00%	90.00%	90.00%
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 54,400,000	$ 57,700,000
Increase (decrease) in net deferred tax liability	100,700,000	51,900,000	$ 44,800,000
Deferred Tax Assets, Valuation Allowance	$ (127,279,000)	(40,114,000)	(80,614,000)
Period in which assets disposition subject to built in gains tax	5 years
Difference in bases for entity not subject to income taxes	$ 3,600,000,000	3,500,000,000
Unrecognized Tax Benefits	6,057,000	12,127,000	12,344,000
Unrecognized tax benefits that, if recognized, would reduce annual effective tax rate	5,300,000	10,700,000
Unrecognized tax benefits, income tax penalties and interest accrued	0
Taxable Reit Subsidiaries
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, valuation allowance	83,200,000	21,200,000	55,100,000
REIT
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, valuation allowance	896,400,000	858,600,000	910,700,000
Tax credit carryforward	10,800,000
Interest Expense Limitation due to Tax Cuts and Jobs Act of 2017
Operating Loss Carryforwards [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ 57,700,000	$ 23,200,000
Net Operating Losses More Likely Than Not To Be Realized [Member]
Operating Loss Carryforwards [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ (95,900,000)