Share-based Payments (Fair Value Assumptions) (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	4.20%	2.20%	0.50%
Expected dividend yield	1.84%	1.74%	1.64%
Expected lives	4 years	4 years	4 years
Expected volatility	35.80%	31.80%	32.30%
Stock options | IAA
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	3.90%
Expected dividend yield	2.05%
Expected lives	2 years
Expected volatility	33.30%
Premium-priced stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate		3.00%	1.10%
Expected dividend yield		1.63%	1.59%
Expected lives		4 years	5 years
Expected volatility		30.20%	30.60%
Performance Share Units With Market Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	4.50%	2.70%
Expected dividend yield	0.00%	1.63%
Expected lives	2 years	2 years
Expected volatility	32.70%	33.40%
Average expected volatility of comparable companies	48.60%	34.40%
Employee Share Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate		5.30%
Expected dividend yield		1.81%
Expected lives		8 months
Expected volatility		28.10%