Taxation (Reconciliation Between Statutory and Effective Tax Rates on Income from Operations) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Statutory rate (percent)	21.00%	21.00%	21.00%
Effect of foreign statutory income tax rates (percent)	(0.50%)	(0.80%)	0.90%
State taxes, net of federal tax effect (percent)	1.90%	1.80%	2.10%
U.S. Tax Reform Impact (percent)	0.00%	0.00%	(1.30%)
Change in valuation allowance for unrecognized tax losses	0.30%	0.50%	0.40%
Share-based compensation (percent)	1.30%	0.90%	(0.20%)
Other (percent)	1.40%	1.90%	(0.50%)
Effect of (income)/losses attributable to noncontrolling interests (percent)	(0.90%)	(1.10%)	0.00%
Effective tax rate per Consolidated Statements of Income (percent)	24.50%	24.20%	22.40%