Consolidated Statements Of Changes In Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Common stock, dividends, per share, declared (in dollars per share)	$ 2.44	$ 2.36	$ 2.36
Adjustments to additional paid in capital, income tax benefit from share-based compensation	$ 0	$ 0	$ 14