A reconciliation of basic and diluted weighted average shares outstanding is as follows:


	Three Months Ended March 31,
	2023		2022
	(Amounts in thousands, except per share data)
Numerator:
Net income	$	28,829	$	46,964
Effect of dilutive securities:
Charges associated with convertible debt instruments, net of tax		—		387
Numerator for diluted earnings per share - net income available to common stockholders after the effect of dilutive securities	$	28,829	$	47,351

Denominator:
Weighted average shares used in computing net income per share - basic		55,590		55,353
Effect of dilutive shares:
Options and stock units		529		726
Convertible senior notes		883		2,726
Contingent consideration		44		—
Dilutive effect of unvested performance stock units		3		11
Dilutive potential common shares		1,459		3,463
Denominator for diluted earnings per share - adjusted weighted average shares used in computing net income per share - diluted		57,049		58,816

Earnings per share:
Basic	$	0.52	$	0.85
Diluted	$	0.51	$	0.81

For the three months ended March 31, 2023 and 2022, 263,871 shares and 137,247 shares, respectively, of the Company’s common stock were excluded from the calculation of diluted EPS because the exercise prices of the stock options were greater than or equal to the average price of the common shares and were therefore anti-dilutive.

In July 2019, the Company issued $287.5 million aggregate principal amount of the 2019 Notes. As provided by the terms of the indenture underlying the 2019 Notes, prior to March 4, 2022, conversion of the 2019 Notes could have been settled in cash, shares of the Company’s common stock or a combination thereof, at the Company’s election. On March 4, 2022, we entered into the Second Supplemental Indenture for the 2019 Notes, which irrevocably elected to settle the conversion of the 2019 Notes using a combination of cash and shares of the Company’s common stock, settling the par value of the 2019 Notes in cash and any excess conversion premium in shares.

As provided by the terms of the Second Supplemental Indenture underlying the 2019 Notes, the Company irrevocably elected to settle the conversion obligation for the 2019 Notes in a combination of cash and shares of the Company's common stock. This means the Company will settle the par value of the 2019 Notes in cash and any excess conversion premium in shares. The Company adopted ASU 2020-06 effective January 1, 2022. Under ASU 2020-06, the Company is required to reflect the dilutive effect of the convertible securities by application of the "if-converted" method, which means the denominator of the EPS calculation would include the total number of shares assuming the 2019 Notes had been fully converted at the beginning of the period. Prior to March 4, 2022, the Company had the choice to settle the conversion of the 2019 Notes in cash, stock or a combination of the two. Therefore, from January 1, 2022 (the date the Company adopted ASU 2020-06) to March 4, 2022, the Company included 3,474,429 shares in the denominator of the EPS calculation, applying the if converted method. Subsequent to March 4, 2022, after the Second Supplemental Indenture became effective, the Company irrevocably elected to settle the conversion obligation for the 2019 Notes in a combination of cash and shares of the Company's common stock, and from March 5, 2022 forward, only the excess premium will be settled with shares. Under the if-converted method of calculating dilutive shares, the Company was also required to exclude amortization of debt issuance costs and interest charges applicable to the convertible debt from the numerator of the dilutive EPS calculation for the period from January 1, 2022 to March 4, 2022, as if the interest on convertible debt was never recognized for that period. For the three months ended March 31, 2022, the Company excluded interest charges of $0.4 million (net of tax) from the numerator.

Prior to the adoption of ASU 2020-06, the Company applied the provisions of ASC 260, “Earnings Per Share,” Subsection 10-45-44, to determine the diluted weighted average shares outstanding as it related to the conversion spread on its convertible notes. Accordingly, the par value of the 2019 Notes was not included in the calculation of diluted income per share, but the dilutive effect of the conversion premium was considered in the calculation of diluted net income per share using the treasury stock method. The dilutive impact of the 2019 Notes was based on the difference between the Company’s current period average stock price and the conversion price of the 2019 Notes, provided there was a premium. Pursuant to this accounting standard, there was no dilution from the accreted principal of the 2019 Notes. For the three months ended March 31, 2023, the dilutive effect of the conversion premium included in the calculation of diluted earnings was 882,599 shares. For the three months ended March 31, 2022, the dilutive effect of the conversion premium included in the calculation of diluted earnings was 2,726,258 shares.