Goodwill and Other Intangible Assets - Schedule of Goodwill and Other Intangible Assets Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, beginning balance	$ 645.5
Amortization of other intangible assets	(10.1)	$ (9.2)
Loss on assets held for sale	(30.2)		$ (30.2)
Goodwill, ending balance	641.4		645.5
Fresh Insurance Services Group Limited
Acquired Finite-Lived Intangible Assets [Line Items]
Proceeds from sale of other assets		1.5
Goodwill
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, beginning balance	645.5	525.5	525.5
Measurement period adjustments	0.0	(0.2)
Amortization of other intangible assets	0.0	0.0
Loss on assets held for sale	0.0	(30.2)
Foreign currency translation	(4.1)	1.5
Goodwill, ending balance	641.4	613.4	645.5
Goodwill | Other
Acquired Finite-Lived Intangible Assets [Line Items]
Measurement period adjustments		0.2
Goodwill | Ark
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill acquired	0.0	116.8
Other
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets (excluding goodwill), beginning balance	420.4	256.9	256.9
Measurement period adjustments	0.0	0.0
Amortization of other intangible assets	(10.1)	(9.2)
Loss on assets held for sale	0.0	0.0
Foreign currency translation	(0.2)	0.2
Other intangible assets (excluding goodwill), ending balance	410.1	423.6	420.4
Other | Ark
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	0.0	175.7
Total Goodwill and Other Intangible Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Other intangible assets, gross (including goodwill), beginning balance	1,065.9	782.4	782.4
Measurement period adjustments	0.0	(0.2)
Amortization of other intangible assets	(10.1)	(9.2)
Loss on assets held for sale	0.0	(30.2)
Foreign currency translation	(4.3)	1.7
Other intangible assets, gross (including goodwill), ending balance	1,051.5	1,037.0	$ 1,065.9
Total Goodwill and Other Intangible Assets | Ark
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill and other intangible assets acquired	$ 0.0	$ 292.5