Shares and Stockholders' Equity (Changes In Common stock (Number Of Shares)) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes In Preferred And Common Stock Number Of Shares [Line Items]
Balance as of beginning-of-period	226,335,105
Balance as of end-of-period	218,090,114	226,335,105
Common Stock [Member]
Changes In Preferred And Common Stock Number Of Shares [Line Items]
Balance as of beginning-of-period	226,335,105	243,835,893	256,551,440
Stock issued for exercise of warrants	344,901	79,397	1,168,966
Stock compensation/issued for benefit plans	1,793,234	1,732,812	2,108,155
Retirement/cancellation of shares	(10,383,126)	(19,312,997)	(15,992,668)
Balance as of end-of-period	218,090,114	226,335,105	243,835,893
Common stock as of end-of-period:
Basic basis	218,090,114	226,335,105	243,835,893
Diluted basis	221,309,830	230,126,820	247,732,609