Earnings Per Common Share

Basic and diluted earnings per common share for the years ended December 31, 2017, 2016 and 2015 were calculated as follows:



	Years Ended December 31,
	2017			2016		2015
	(Dollars in millions, except per share amounts, shares in thousands)
Income (Numerator):
Net income	$	1,389		626		878
Earnings applicable to non-vested restricted stock	—			—		—
Net income applicable to common stock for computing basic earnings per common share	1,389			626		878
Net income as adjusted for purposes of computing diluted earnings per common share	$	1,389		626		878
Shares (Denominator):
Weighted average number of shares:
Outstanding during period	635,576			545,946		559,260
Non-vested restricted stock	(7,768		)	(6,397	)	(4,982	)
Weighted average shares outstanding for computing basic earnings per common share	627,808			539,549		554,278
Incremental common shares attributable to dilutive securities:
Shares issuable under convertible securities	10			10		10
Shares issuable under incentive compensation plans	875			1,120		805
Number of shares as adjusted for purposes of computing diluted earnings per common share	628,693			540,679		555,093
Basic earnings per common share	$	2.21		1.16		1.58
Diluted earnings per common share	$	2.21		1.16		1.58

Our calculation of diluted earnings per common share excludes shares of common stock that are issuable upon exercise of stock options when the exercise price is greater than the average market price of our common stock. We also exclude unvested restricted stock awards that are antidilutive as a result of unrecognized compensation cost. Such shares averaged 4.7 million, 3.3 million and 3.1 million for 2017, 2016 and 2015, respectively.