Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Share-based Compensation [Abstract]

Compensation Expense And Related Tax Benefit For All Share-Based Awards

(In millions)	2017		2016		2015
Compensation expense	$	25	$	26	$	25
Reduction of income tax expense	19		9		8

Summary Of Stock Option Activity

	Number of shares		Weighted average exercise price
Balance at December 31, 2014	5,630,502		$	31.60
Granted	740,300		29.01
Exercised	(1,165,287	)	25.11
Expired	(1,322,067	)	48.44
Forfeited	(79,353	)	28.09
Balance at December 31, 2015	3,804,095		27.30
Granted	789,651		21.25
Exercised	(1,055,532	)	23.75
Expired	(56,297	)	61.60
Forfeited	(44,007	)	27.66
Balance at December 31, 2016	3,437,910		26.44
Granted	195,882		44.18
Exercised	(941,761	)	26.03
Expired	(58,257	)	66.20
Forfeited	(73,203	)	25.63
Balance at December 31, 2017	2,560,571		27.06
Outstanding stock options exercisable as of:
December 31, 2017	1,648,367		$	26.55
December 31, 2016	1,892,136		27.60
December 31, 2015	2,187,259		26.35