Reserves (Roll Forward of Claims and Benefits Payable) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Claims and benefits payable, at beginning of year		$ 2,813.7	$ 3,782.2	$ 3,301.2
Less: Reinsurance ceded and other		(2,053.7)	(3,193.3)	(2,718.2)
Net claims and benefits payable, at beginning of year		760.0	588.9	583.0
Acquired reserves as of Acquisition Date	$ 140.7	0.0	140.7	0.0
Incurred losses and loss adjustment expenses related to:
Incurred losses and loss adjustment expenses, current year		2,670.9	2,353.0	1,965.0
Incurred losses and loss adjustment expenses, prior year(s)		(16.2)	(7.4)	(58.5)
Total incurred losses and loss adjustment expenses		2,654.7	2,345.6	1,906.5
Paid losses and loss adjustment expenses related to:
Paid losses and loss adjustment expenses, current year		2,097.8	1,887.1	1,536.4
Paid losses and loss adjustment expenses, prior year(s)		529.2	428.1	364.2
Total paid losses and loss adjustment expenses		2,627.0	2,315.2	1,900.6
Net claims and benefits payable, at end of year	760.0	787.7	760.0	588.9
Plus: Reinsurance ceded and other	2,053.7	1,900.0	2,053.7	3,193.3
Claims and benefits payable, at end of year	2,813.7	2,687.7	$ 2,813.7	$ 3,782.2
Reinsurance recoverables		$ 9,596.2
Time Insurance Company
Liability for Claims and Claims Adjustment Expense [Line Items]
Increase in reserve and reinsurance recoverable	$ 730.0