Income Taxes (Reconciliation From Statutory Federal Income Tax Rate To Effective Income Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	35.00%	35.00%	35.00%
State tax on commercial operations, net of federal benefits	0.60%	0.60%	0.50%
Impact of international operations	(4.50%)	(4.00%)	(1.30%)
Domestic production deduction	(1.50%)	(1.50%)	(1.60%)
Equity-based compensation	(2.60%)	(2.30%)	0.00%
Domestic tax credits	(0.80%)	(0.90%)	(1.10%)
Contract close-outs	0.00%	0.00%	(2.80%)
Impact of change in U.S. tax law	2.90%	0.00%	0.00%
Other, net	(0.50%)	(0.20%)	(0.70%)
Effective income tax rate	28.60%	26.70%	28.00%