Income Taxes (Reconciliation Of The Statutory Federal Income Tax Rate To The Effective Tax Rate) (Details)		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	21.00%	21.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Percent [Abstract]
State income taxes (net of federal income tax benefit)		0.90%	0.80%	0.60%
Foreign rate differential		(0.30%)	(11.60%)	(10.20%)
Resolution and expiration of statutes of limitation of uncertain tax positions		(1.70%)	(6.50%)	(3.10%)
Permanent foreign exchange losses		0.00%	(0.60%)	(8.20%)
Research credits, uncertain tax positions and other		(0.60%)	(1.00%)	3.40%
TCJA - revaluation of U.S. deferred income taxes		(1.40%)	(41.50%)	0.00%
TCJA - Transition Tax		1.60%	41.40%	0.00%
Effective income tax rate		19.50%	16.00%	17.50%