Income Taxes - Reasons for Income Tax Provision Differences to Statutory Rate (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Tax at U.S. statutory rate (as a percent)	21.00%	21.00%	21.00%
Changes in taxes resulting from :
Low income housing tax credits (as a percent)	(2.00%)	(4.30%)	(3.60%)
State taxes, net of federal benefit (as a percent)	1.80%	2.10%	2.40%
Incentive compensation (as a percent)	(1.60%)	(1.40%)
Dividend received deduction (as a percent)		(2.10%)	(1.80%)
Foreign tax credits, net of addback (as a percent)			(2.20%)
Other, net (as a percent)	(1.60%)	0.90%	(0.60%)
Income tax provision (as a percent)	17.60%	16.20%	15.20%