Summary of Significant Accounting Policies Stock-Based Compensation (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares authorized for issuance	9,000,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)	3 years
Minimum exercise price of stock option as a percent of common stock fair value on the grant date	100.00%
Period after the grant date during which stock options can't be exercised (in months)	6 months
Maximum term of awards (in years)	10 years
Stock options granted (in shares)	530,612	554,594	476,418
Estimated weighted-average fair value per stock option (in dollars per share)	$ 13.20	$ 10.94	$ 8.60
Risk-free interest rate, minimum (as a percent)	0.10%	0.20%	2.50%
Risk-free interest rate, maximum (as a percent)	0.90%	1.90%	2.70%
Dividend yield (as a percent)	2.90%	3.00%	3.60%
Expected volatility (as a percent)	21.00%	16.30%	17.00%
Expected life (in years)	8 years 8 months 12 days	8 years 7 months 6 days	8 years 6 months
Restricted stock | Employees
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)	3 years
Percentage to vest each year after grant date	33.00%
Restricted stock | Directors
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)	1 year
Performance units
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (in years)	3 years
Maximum adjustment to payout ratio	10.00%
Performance units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award
Payout ratio (as a percent)	0.00%
Performance units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award
Payout ratio (as a percent)	175.00%