Commitments and Contingencies - Assets and Liabilities of Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 100.0	$ 69.0
Finance lease asset	2.0
Total lease assets	102.0
Operating lease liabilities	130.0	$ 95.0
Finance lease liabilities	2.0
Total lease liability	$ 132.0
Operating Lease, Weighted Average Remaining Lease Term	9 years 4 months 24 days
Operating Lease, Weighted Average Discount Rate, Percent	2.61%
Finance Lease, Weighted Average Remaining Lease Term	1 year 9 months 18 days
Finance Lease, Weighted Average Discount Rate, Percent	1.74%
Finance Lease amortization	$ 0.1