Net Income Per Common Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Calculations For Basic And Diluted Earnings Per Share

The table shows calculations for basic and diluted earnings per share:

(In millions, except per share data)	Years ended December 31,
	2017		2016		2015
Numerator:
Net income—basic and diluted	$	1,045	$	591	$	634
Denominator:
Basic weighted-average common shares outstanding	164.2		164.5		164.0
Effect of share-based awards:
Stock options	1.1		1.1		1.0
Nonvested shares	0.7		0.9		0.6
Diluted weighted-average shares	166.0		166.5		165.6
Earnings per share:
Basic	$	6.36	$	3.59	$	3.87
Diluted	6.29		3.55		3.83
Number of anti-dilutive share-based awards	0.7		0.3		0.4