Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Statutory U.S. Federal tax rate	21.00%	21.00%	21.00%
Increase (decrease) in tax rate resulting from:
State taxes—net of Federal benefit	5.80%	4.90%	4.80%
Excess executive compensation	1.40%	0.70%	0.80%
Research and development credit	(1.10%)	(1.80%)	(8.80%)
Stock-based compensation	(1.10%)	(0.90%)	(1.30%)
ESSP	(0.60%)	(0.70%)	(1.00%)
Other, net	0.40%	(0.30%)	0.80%
Effective tax rate	25.80%	22.90%	16.30%