Income Taxes (Reconciliation Of U.S. Federal Statutory Tax Rate To Consolidated Effective Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal statutory tax rate	21.00%	21.00%	35.00%
State income taxes, net of federal benefit	1.50%	1.50%	1.10%
Foreign rate differential	0.80%	0.80%	0.10%
Uncertain tax positions	(0.20%)	0.50%	0.30%
U.S. tax reform enactment	(0.40%)	0.20%	4.50%
Effective income tax rate reconciliation, change in deferred tax assets valuation allowance, percent	(1.30%)	0.00%	0.00%
Domestic production activity benefit	0.00%	0.00%	(2.60%)
Benefit from entity restructuring	0.00%	(1.40%)	0.00%
Research and development credits	(2.20%)	(2.30%)	(1.40%)
Stock-based compensation	(3.10%)	(3.30%)	(3.10%)
Foreign-derived intangible income deduction	(3.80%)	(3.90%)	0.00%
Other	1.30%	0.80%	0.60%
Consolidated effective tax rate	13.60%	13.90%	34.50%