INCOME 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 March 31,
	2018		2017
Numerator (basic and diluted):
Net income	$	149	$	138
Less: Allocation to unvested restricted stock awards	1		1
Net income available to common shareholders	$	148	$	137

Denominator:
Basic common shares (based upon weighted average)	310		317
Add: Stock option dilution	3		4
Diluted common shares	313		321

For the three-month periods ended March 31, 2018 and 2017, we allocated dividends and undistributed earnings to the unvested restricted stock awards.

Additionally, 431,000 and 221,000 common shares for the three-month periods ended March 31, 2018 and 2017, respectively, related to stock options were excluded from the computation of diluted income per common share due to their antidilutive effect.

In May 2017, our Board of Directors authorized the repurchase, for retirement, of up to $1.5 billion of shares of our common stock in open-market transactions or otherwise, replacing the previous Board of Directors authorization established in 2014. In February 2018, we agreed to repurchase a total of $150 million of common stock with an immediate delivery of 2.8 million shares under an accelerated stock repurchase transaction. In March 2018, upon completion of the transaction, we received, at no cost to us, an additional 0.9 million shares of our common stock resulting from changes in the volume weighted average stock price of our common stock over the term of the transaction. In total, we repurchased and retired 3.7 million shares of our common stock in the first three months of 2018 (including 0.6 million shares to offset the dilutive impact of long-term stock awards granted in the first three months of the year). At March 31, 2018, we had $1.1 billion remaining under the 2017 authorization.

On the basis of amounts paid (declared), cash dividends per common share were $0.105 ($0.105) and $0.100 ($0.100) for the three-month periods ended March 31, 2018 and 2017, respectively.