CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 112.3	$ 147.4
Other comprehensive income (loss), before tax:
Unrealized losses on investments	(2,435.1)	(1,198.2)
Adjustment to present value of future profits and deferred acquisition costs	257.5	83.6
Amount related to premium deficiencies assuming the net unrealized losses had been realized	165.0	262.5
Reclassification adjustments:
For net realized investment (gains) losses included in net income	7.8	(0.5)
For amortization of the present value of future profits and deferred acquisition costs related to net realized investment (gains) losses included in net income	(0.1)	0.0
Other comprehensive loss before tax	(2,004.9)	(852.6)
Income tax benefit related to items of accumulated other comprehensive income	438.3	184.6
Other comprehensive loss, net of tax	(1,566.6)	(668.0)
Comprehensive loss	$ (1,454.3)	$ (520.6)