Income Taxes (Effective Income Tax Rate Reconciliation) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Statutory rate	21.00%	21.00%	21.00%	21.00%
State taxes, net of federal tax benefit	3.20%	3.30%	3.20%	3.20%
Foreign tax expense and tax rate differential	(0.10%)	(0.20%)	(0.10%)	(0.10%)
Tax benefit from stock option exercises	(1.20%)	(0.40%)	(1.20%)	(1.30%)
Other, net	(0.60%)	(0.40%)	(0.40%)	(0.40%)
Effective income tax rate	22.30%	23.30%	22.50%	22.40%