INCOME PER COMMON SHARE

12 Months Ended

Dec. 31, 2022

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


	Year Ended December 31,
	2022		2021		2020
Numerator (basic and diluted):
Income from continuing operations	$	844	$	410	$	810
Less: Allocation to redeemable noncontrolling interest	(2)		2		—
Less: Allocation to unvested restricted stock awards	4		2		6
Income from continuing operations attributable to common shareholders	842		406		804
Income from discontinued operations, net	—		—		414
Less: Allocation to unvested restricted stock awards	—		—		3
Income from discontinued operations, net attributable to common shareholders	—		—		411
Net income attributable to common shareholders	$	842	$	406	$	1,215

Denominator:
Basic common shares (based upon weighted average)	231		249		264
Add: Stock option dilution	1		2		—
Diluted common shares	232		251		264

We follow accounting guidance regarding determining whether instruments granted in share-based payment transactions are participating securities. This accounting guidance clarifies that share-based payment awards that entitle their holders to receive non-forfeitable dividends prior to vesting should be considered participating securities. The dividends associated with the unvested restricted stock units are forfeitable, and consequently, the restricted stock units are not considered a participating security and are not accounted for under the two-class method. We have also granted restricted stock awards that contain non-forfeitable rights to dividends on unvested shares; such unvested restricted stock awards are considered participating securities. As participating securities, the unvested shares are required to be included in the calculation of our basic income per common share, using the two-class method. The two-class method of computing income per common share is an allocation method that calculates income per share for each class of common stock and participating security according to dividends declared and participation rights in undistributed earnings. For the years ended December 31, 2022, 2021 and 2020, we allocated dividends and undistributed earnings to the participating securities.

The following stock options, restricted stock units and performance restricted stock units were excluded from the computation of weighted-average diluted common shares outstanding due to their anti-dilutive effect, in thousands:


	Year Ended December 31,
	2022	2021	2020
Number of stock options	635	296	374
Number of restricted stock units	20	—	—
Number of performance restricted stock units	15	—	—

INCOME PER COMMON SHARE (Concluded)Common shares outstanding included on our balance sheet and for the calculation of income per common share do not include unvested stock awards (273,000 and 608,000 common shares at December 31, 2022 and 2021, respectively); shares outstanding for legal requirements included all common shares that have voting rights (including unvested stock awards).