Insurance Expenses (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Insurance Expenses [Abstract]
Commissions									$ 745.8	$ 708.8	$ 558.7
General Expenses									307.4	278.0	231.9
Taxes, Licenses and Fees									94.2	93.5	71.0
Total Costs Incurred									1,147.4	1,080.3	861.6
Policy Acquisition Costs:
Deferred									(693.4)	(475.2)	(481.5)
Amortized									641.8	408.3	377.1
Net Policy Acquisition Costs Amortized (Deferred)									(51.6)	(66.9)	(104.4)
Amortization of VOBA									4.7	6.3	143.3
Insurance Expenses	$ 279.3	$ 276.9	$ 272.7	$ 271.6	$ 265.4	$ 256.0	$ 263.5	$ 234.8	$ 1,100.5	$ 1,019.7	$ 900.5