Summary of Significant Accounting Policies - Schedule of Changes in Restructuring Reserve (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	$ 46.1	$ 7.3
Severance costs	15.2	74.2
Office closure costs		27.3
Other costs		9.2
Costs paid, utilized or transferred out	(38.0)	(71.9)
Balance at end of year	23.3	46.1
Reportable segments | Americas
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	1.9	0.4
Severance costs	5.2	5.5
Office closure costs		19.6
Other costs		4.4
Costs paid, utilized or transferred out	(6.1)	(28.0)
Balance at end of year	1.0	1.9
Reportable segments | Southern Europe
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	3.5	0.7
Severance costs	0.0	16.2
Office closure costs		5.1
Other costs		3.2
Costs paid, utilized or transferred out	(2.7)	(21.7)
Balance at end of year	0.8	3.5
Reportable segments | Northern Europe
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	40.7	6.2
Severance costs	10.0	49.8
Office closure costs		2.1
Other costs		0.5
Costs paid, utilized or transferred out	(29.2)	(17.9)
Balance at end of year	21.5	40.7
Reportable segments | APME
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	0.0	0.0
Severance costs	0.0	2.5
Office closure costs		0.5
Other costs		1.1
Costs paid, utilized or transferred out	0.0	(4.1)
Balance at end of year	0.0	0.0
Corporate
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	0.0	0.0
Severance costs	0.0	0.2
Office closure costs		0.0
Other costs		0.0
Costs paid, utilized or transferred out	0.0	(0.2)
Balance at end of year	$ 0.0	$ 0.0