Life, Accident and Health Reserves - By Product Line (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total life, accident and health reserves	$ 4,593.9	$ 4,567.1
Long-term care insurance reserves
Liability for Claims and Claims Adjustment Expense [Line Items]
Total life, accident and health reserves	4,231.0	4,201.6
Traditional life insurance reserves
Liability for Claims and Claims Adjustment Expense [Line Items]
Total life, accident and health reserves	170.6	173.4
Other accident and health insurance reserves
Liability for Claims and Claims Adjustment Expense [Line Items]
Total life, accident and health reserves	$ 192.3	$ 192.1