Computation of Basic/Diluted Earnings Per Common Share

The following table sets forth the computation of basic and diluted earnings per common share (amounts in millions, except per share data):



	For the Years Ended December 31,
	2018		2017		2016
Numerator:
Consolidated net income	$	1,813	$	273	$	966
Less: Distributed earnings to unvested share-based awards that participate in earnings	—		—		(2		)
Less: Undistributed earnings allocated to unvested share-based awards that participate in earnings	—		—		(2		)
Numerator for basic and diluted earnings per common share—income available to common shareholders	$	1,813	$	273	$	962

Denominator:
Denominator for basic earnings per common share—weighted-average common shares outstanding	762		754		740
Effect of dilutive stock options and awards under the treasury stock method	9		12		14
Denominator for diluted earnings per common share—weighted-average common shares outstanding plus dilutive common shares under the treasury stock method	771		766		754
Basic earnings per common share	$	2.38	$	0.36	$	1.30
Diluted earnings per common share	$	2.35	$	0.36	$	1.28

In 2016, certain of our unvested restricted stock units met the definition of participating securities, as they participated in earnings based on their rights to dividends or dividend equivalents. Therefore, we were required to use the two-class method in our computation of basic and diluted earnings per common share. For the year ended December 31, 2016, on a weighted-average basis, we had outstanding unvested restricted stock units of 3 million shares of common stock that participated in earnings.

The vesting of certain of our employee-related restricted stock units and options is contingent upon the satisfaction of pre-defined performance measures. The shares underlying these equity awards are included in the weighted-average dilutive common shares only if the performance measures are met as of the end of the reporting period. Approximately 4 million, 7 million, and 8 million shares are not included in the computation of diluted earnings per common share for the years ended December 31, 2018, 2017, and 2016, respectively, as their underlying performance measures had not yet been met.

Potential common shares are not included in the denominator of the diluted earnings per common share calculation when the inclusion of such shares would be anti-dilutive. Therefore, 3 million, 1 million, and 5 million options to purchase shares of common stock were not included in the calculation of diluted earnings per common share for the years ended December 31, 2018, 2017, and 2016, respectively, as the effect of their inclusion would be anti-dilutive.