Income Per Common Share (Tables)

9 Months Ended

Sep. 30, 2018

Earnings Per Share [Abstract]

Schedule of reconciliations of the numerators and denominators used in the computations of basic and diluted earnings per common share

Reconciliations of the numerators and denominators used in the computations of basic and diluted income per common share were as follows, in millions: 

	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Numerator (basic and diluted):
Net income	$	180	$	152	$	540	$	453
Less: Allocation to unvested restricted stock awards	1		1		5		4
Net income available to common shareholders	$	179	$	151	$	535	$	449
Denominator:
Basic common shares (based upon weighted average)	304		313		307		315
Add: Stock option dilution	2		3		2		4
Diluted common shares	306		316		309		319