Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Income Taxes [Line Items]
Reconciliation of provision for income taxes on continuing operations at the statutory U.S. Federal tax rate	35.00%
Valuation allowance recognized	$ 70.2	$ 292.9
Net change in valuation allowance	(222.6)	$ 25.6
Net federal operating tax loss carry-forward	$ 1,200.0
Operating loss carry-forward, expiration year	2017
Foreign net operating loss carry-forward	$ 66.6
Net state operating tax loss carry-forward	502.0
Undistributed earnings of Company's foreign subsidiaries	92.8
Undistributed earnings of Company's foreign subsidiaries permanently reinvested	60.3
Undistributed earnings of foreign subsidiaries, federal and state income taxes	0.0
Real Estate Investment Trust [Member]
Schedule Of Income Taxes [Line Items]
Net federal operating tax loss carry-forward	1,100.0
Accounting Standards Update 2016-09 [Member]
Schedule Of Income Taxes [Line Items]
Excess tax deductions	27.3
Restatement Adjustment [Member] | Real Estate Investment Trust [Member]
Schedule Of Income Taxes [Line Items]
Net deferred tax assets	$ (205.3)
Minimum [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carry-forward, expiration year	2021
Maximum [Member]
Schedule Of Income Taxes [Line Items]
Operating loss carry-forward, expiration year	2036