Earnings Per Common Share

Nonvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents are participating securities and are included in the computation of earnings per share pursuant to the two-class method. The two-class method is an earnings allocation formula that determines earnings per share for each class of common stock and participating security according to dividends declared (or accumulated) and participation rights in undistributed earnings. Certain of the Company's nonvested restricted stock awards qualify as participating securities.

Net earnings is allocated between the common stock and participating securities pursuant to the two-class method. Basic earnings per common share is computed by dividing net earnings available to common shareholders by the weighted average number of common shares outstanding during the period, excluding participating nonvested restricted shares.

Diluted earnings per common share is computed in a similar manner, except that first the denominator is increased to include the number of additional common shares that would have been outstanding if potentially dilutive common shares, excluding the participating securities, were issued using the treasury stock method. For all periods presented, stock options, restricted stock awards and restricted stock units are the only potentially dilutive non-participating instruments issued by the Company. Next, we determine and include in diluted earnings per common share calculation the more dilutive effect of the participating securities using the treasury stock method or the two-class method. Undistributed losses are not allocated to the nonvested share-based payment awards (the participating securities) under the two-class method as the holders are not contractually obligated to share in the losses of the Company.

The following is a computation of basic and diluted earnings per common share for the three months ended March 31, 2018 and 2017:



(in thousands, except per share data)	Three Months Ended
	March 31, 2018		March 31, 2017
NUMERATORS:
Net income	$	77,669	$	46,003
Less:
Dividends and undistributed earnings allocated to participating securities (1)	6		12
Net earnings available to common shareholders	$	77,663	$	45,991
DENOMINATORS:
Weighted average number of common shares outstanding - basic	220,370		220,287
Effect of potentially dilutive common shares (2)	455		492
Weighted average number of common shares outstanding - diluted	220,825		220,779
EARNINGS PER COMMON SHARE:
Basic	$	0.35	$	0.21
Diluted	$	0.35	$	0.21


(1)	Represents dividends paid and undistributed earnings allocated to certain nonvested restricted stock awards.


(2)	Represents the effect of the assumed exercise of stock options, vesting of non-participating restricted shares, and vesting of restricted stock units, based on the treasury stock method.

The following table presents the weighted average outstanding securities that were not included in the computation of diluted earnings per common share because their effect would be anti-dilutive for the three months ended March 31, 2018 and 2017.



(in thousands)	Three Months Ended
	March 31, 2018	March 31, 2017
Stock options	—	36