Income Taxes (Narrative) (Details) - USD ($) $ in Millions		12 Months Ended
	Dec. 22, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Income Taxes [Line Items]
Effective income tax rate			35.00%
Valuation allowance recognized			$ 38.8	$ 70.2
Net change in valuation allowance			31.4	$ 222.6
Net federal operating tax loss carry-forward			1,100.0
Net foreign operating loss carry-forward			79.5
Net state operating tax loss carry-forward			456.1
Undistributed earnings of Company's foreign subsidiaries			102.2
One-time income inclusion of unremitted earnings as a result of the Tax Act	$ 52.4
Real Estate Investment Trust [Member]
Schedule Of Income Taxes [Line Items]
Net federal operating tax loss carry-forward			$ 956,700.0
Scenario, Plan [Member]
Schedule Of Income Taxes [Line Items]
Effective income tax rate		21.00%
Minimum [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carry-forward, expiration year			2022
Foreign and state operating tax loss carry forwards expiration date			2018
Maximum [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carry-forward, expiration year			2036