Income Taxes - Income Tax (Benefit) Expense Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
U.S. federal statutory tax rate	35.00%	35.00%	35.00%
Taxes computed at U.S. statutory rate	$ (101.2)	$ (16.8)	$ (80.3)
State income taxes, net of federal benefit	0.9	0.1	(3.6)
Net change in reserve	(8.1)	(24.1)	27.5
Change in valuation allowances	83.2	68.4	72.6
Provision for tax on undistributed foreign earnings	(1.0)	26.8	5.0
Change of tax rate	(19.4)	11.8	(1.0)
Impact of transaction costs	0.0	(24.5)	40.5
Settlement of Series B Convertible Preferred Stock	0.0	(34.3)	0.0
Goodwill impairment	53.4	6.2	0.0
Provisional estimate of TCJA	(46.3)	0.0	0.0
Other, net	2.3	3.2	8.6
Income tax expense	$ 6.6	$ 28.6	$ 75.1
Effective tax rate	(2.30%)	(59.50%)	(32.80%)
Foreign
Income Taxes [Line Items]
Tax on foreign operations	$ (3.9)	$ (17.2)	$ (25.3)
Domestic
Income Taxes [Line Items]
Tax on foreign operations	$ 46.7	$ 29.0	$ 31.1