Investments - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Net Investment Income [Line Items]
Investment grade rating	95.20%
FHLB funding agreements	$ 792.5	$ 787.5
Investment Grade
Net Investment Income [Line Items]
Increase in credit spread (percent)	0.40%
Decrease in total returns (percent)	15.40%
Increase to Bloomberg Barclays Index Yield-To-Worst (percent)	3.10%
Bloomberg Barclays Index Yield-to-Worst	5.40%
High Yield Index
Net Investment Income [Line Items]
Increase in credit spread (percent)	1.71%
Decrease in total returns (percent)	11.20%
Increase to Bloomberg Barclays Index Yield-To-Worst (percent)	4.80%
Bloomberg Barclays Index Yield-to-Worst	9.00%
Ten Year United States Treasury
Net Investment Income [Line Items]
Increase in interest rates	2.36%
Federal interest rate on securities (percent)	3.87%	1.51%
FHLB of Chicago
Net Investment Income [Line Items]
Fair Value	$ 860.4	$ 870.1
Governmental agencies as required by law in various states
Net Investment Income [Line Items]
Fair Value	$ 28.6	$ 26.2