Income Taxes - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 31, 2018	Dec. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Income Tax Disclosure [Line Items]
Federal corporate tax rate	21.00%	34.00%	32.92%
Valuation allowance (decrease) increase, amount			$ (27.0)	$ 44.2
Provisional tax expense associated with remeasurement of deferred tax balances			89.7
Federal
Income Tax Disclosure [Line Items]
Net operating loss carry forwards	$ 624.7		624.7
Tax credit carry forward	18.2		$ 18.2
Operating loss carryforwards expiration year			2025
Research and development tax credit carryforwards expiration year			2025
State
Income Tax Disclosure [Line Items]
Net operating loss carry forwards	613.7		$ 613.7
Tax credit carry forward	20.8		$ 20.8
Operating loss carryforwards expiration year			2028
Foreign
Income Tax Disclosure [Line Items]
Net operating loss carry forwards	$ 214.7		$ 214.7