Taxation (Reconciliation of Changes in Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance	$ 69.9	$ 20.0	$ 19.6
Additions for tax positions related to the current year	6.6	1.4	1.0
Additions for tax positions related to prior years	2.2	1.2	0.1
Additions for tax positions related to prior years of acquired entities		54.1
Reductions for tax positions related to prior years		(4.0)	(0.2)
Reductions related to settlements	(9.9)
Reductions related to lapse of statute of limitations	(6.9)	(2.8)	(0.5)
Balance	$ 61.9	$ 69.9	$ 20.0