Contract Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Receivables from contract with customers	$ 257.9	$ 185.0
Unearned revenues from contract with customers	89.8	87.6
Upfront costs in connection with client contracts	696.2	540.2
Service Contracts And Sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer, liability, unearned revenue		43.3	$ 57.9
Upfront costs in connection with client contracts	13.8	25.8
Global Lifestyle
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Disaggregated fee revenues	714.1	852.8	693.1
Global Housing
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Disaggregated fee revenues	$ 95.6	$ 104.1	$ 241.9