Earnings Per Share

Basic earnings per share is computed using the weighted-average number of outstanding shares of common stock during the period. Diluted earnings per share is computed using the weighted-average number of outstanding shares of common stock and, when dilutive, potential common shares outstanding during the period. Potential common shares consist of incremental shares issuable upon the assumed exercise of stock options. The computation of earnings per share is as follows:



	Three Months Ended
	March 31, 2018		March 31, 2017
	(in thousands, except per share data)
Basic earnings per share:
Net income	$	290,124	$	178,222
Shares used in computation:
Weighted-average common shares outstanding	434,174		430,600
Basic earnings per share	$	0.67	$	0.41

Diluted earnings per share:
Net income	$	290,124	$	178,222
Shares used in computation:
Weighted-average common shares outstanding	434,174		430,600
Employee stock options	16,185		14,858
Weighted-average number of shares	450,359		445,458
Diluted earnings per share	$	0.64	$	0.40

Employee stock options with exercise prices greater than the average market price of the common stock were excluded from the diluted calculation as their inclusion would have been anti-dilutive. These anti-dilutive stock options were immaterial for each period presented.