Liability for Unpaid Claims and CAE Liability for Unpaid Claims - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Liability for Claims and Claims Adjustment Expense - Narrative Information
Long-term Care Reserve Increase, Before Tax	$ 750.8	$ 750.8
Long-term Care Reserve Increase, After Tax	$ 593.1	593.1
Claim Reserve
Liability for Claims and Claims Adjustment Expense - Narrative Information
Long-term Care Reserve Increase, Before Tax		$ 236.0