Business and Summary of Significant Accounting Policies - Trade and Notes Receivable (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue Recognition, Milestone Method [Line Items]
Insurance commissions as percentage of agent premiums	77.10%	76.70%	76.40%
Premium due from agents, net of accrued sales commissions	$ 74	$ 113
Minimum
Revenue Recognition, Milestone Method [Line Items]
Accrual for agency premiums, time lag period	7 months
Accrual for agency premiums reported within three months, percent	66.00%
Accrual for agency premiums reported within next three months, percent	10.00%
Maximum
Revenue Recognition, Milestone Method [Line Items]
Accrual for agency premiums, time lag period	15 months
Accrual for agency premiums reported within three months, percent	85.00%
Accrual for agency premiums reported within next three months, percent	24.00%