Year Ended December 31,

2019

2018

2017

(Dollars in thousands, except per share amounts)

Numerator

Net income

$

238,312

$

210,780

$

141,835

Less: distributed earnings allocated to participating securities

(466

)

(413

)

(257

)

Less: undistributed earnings allocated to participating securities

(1,020

)

(846

)

(441

)

Net income attributable to common stockholders (numerator for basic earnings per share)

236,826

209,521

141,137

Add back: undistributed earnings allocated to participating securities

1,020

846

441

Less: undistributed earnings reallocated to participating securities

(992

)

(833

)

(431

)

Numerator for diluted earnings per share under two class method

$

236,854

$

209,534

$

141,147

Denominator

Weighted-average common shares outstanding

61,616,988

60,571,123

60,117,021

Add: dilutive effect of stock options

1,737,945

984,076

1,336,557

Add: dilutive effect of performance share units

347,733

275,562

-

Denominator for diluted earnings per share under two class method

63,702,666

61,830,761

61,453,578

Basic Earnings Per Common Share

$

3.84

$

3.46

$

2.35

Diluted Earnings Per Common Share

$

3.72

$

3.39

$

2.30