Stockholders' Equity (Reconciliation Of Denominators Used In Computation Of Basic And Diluted Earnings Per Share) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stockholders' Equity Note [Abstract]
Basic weighted average shares outstanding (in shares)	288,208,435	288,949,525	291,453,107
Weighted shares assumed upon exercise of stock options (in shares)	134,298	207,998	592,335
Diluted weighted average shares outstanding (in shares)	288,342,733	289,157,523	292,045,442