Litigation, Commitments and Contingencies - Operating Leases (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) renewal_term	Dec. 31, 2016 USD ($)
Operating Leased Assets [Line Items]
Number of renewal terms (or more) | renewal_term	1
Operating Leases, Rent Expense, Net [Abstract]
Minimum lease payments	$ 1.2	$ 3.6
Contingent rentals	0.0	(2.0)
Total rental expense, net	1.2	$ 1.6
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018	0.7
2019	0.4
2020	0.2
2021	0.1
2022	0.1
Thereafter	0.1
Total	$ 1.6
Minimum
Operating Leased Assets [Line Items]
Operating lease renewal term	1 year
Maximum
Operating Leased Assets [Line Items]
Operating lease renewal term	3 years