Leases - Lease Cash Flow and Supplemental Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 3.2	$ 3.2	$ 9.6	$ 9.4
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 0.3	$ 0.3	$ 4.6	$ 8.4