Leases - Components of Lease Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating lease cost:
Amortization of right-of-use assets	$ 2.7
Interest on lease liabilities	0.6
Total operating lease cost	$ 3.3
Operating lease cost		$ 3.3	$ 1.6