Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Provisional estimate of TCJA	$ (46.3)	$ 0.0	$ 0.0
Undistributed foreign earnings	21.9	36.8
Adjustment of valuation allowance	20.1
Valuation allowance	391.7	383.3
Increase (decrease) in valuation allowance	8.4
State operating loss carry forward	591.0
State tax credits	841.0
Foreign operating loss carry forward	774.0
Valuation allowance on foreign tax credit carryovers	43.2
Research and development credits	17.8
State tax credits (net of federal tax)	$ 6.5
Tax carry-forward period	10 years
Unrecognized tax benefit	$ 90.3	128.3	112.2	$ 27.7
Reduction in effective tax rate	39.8
Provisional estimate of unrecognized tax benefits	28.7
Total unrecognized benefits expected to revers within the next twelve months	4.2
Interest and penalties related to unrecognized tax benefits	(1.2)	(5.5)	$ 4.9
Accrued interest and penalties related to unrecognized tax benefits	$ 13.0	$ 13.3

Amount of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations, attributable to increase (decrease) in income tax rate and transition tax on accumulated earnings of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act of 2017.

No definition available.