Income Taxes - Differences Between Statutory Income Tax Rate and Effective Income Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Increase (decrease) resulting from:
Tax at statutory rate	$ 200	$ 56
Tax-exempt income from municipal bonds	(5)	(5)
Dividend received exclusion	(5)	(5)
Other	8	(3)
Total provision for income taxes	$ 198	$ 43
Increase (decrease) resulting from:
Tax at statutory rate	21.00%	21.00%
Tax-exempt income from municipal bonds, Percent	(0.50%)	(1.90%)
Dividend received exclusion, Percent	(0.50%)	(1.90%)
Other	0.80%	(1.20%)
Provision for income taxes	20.80%	16.00%