Leases - Cash flows (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases
Operating cash flows from operating leases	$ 3.0
Financing cash flows from finance leases	0.4
Total cash paid for amounts included in the measurement of lease liabilities	3.4
Operating lease liabilities arising from obtaining right-of-use assets	$ 0.3