Supplemental disclosures of cash flow information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Components and classification of cash, restricted cash and equivalents
Cash and cash equivalents	$ 172.5		$ 286.6
Restricted cash classified as other assets	2.6		2.6
Total	175.1	$ 348.9	$ 289.2	$ 189.3
Cash flows from operating activities:
Cash paid for income taxes, net	12.6	12.2
Cash paid for interest	64.0	27.2
Cash paid under operating leases	10.7	10.0
Cash paid under finance leases	1.3	1.3
Cash flows from financing activities:
Cash paid under finance leases	$ 1.1	$ 1.1