Basic and diluted earnings per share is computed using the two-class method. The two-class method is an earnings allocation formula that determines net income per share for each class of common stock and participating security according to dividends declared and participation rights in undistributed earnings. Per share amounts are computed by dividing net income from continuing operations attributable to common shareholders by the weighted average shares outstanding during each period.

The computations of basic and diluted earnings per share from continuing operations are as follows:



(in 000s, except per share amounts)
Year ended April 30,	2017			2016			2015
Net income from continuing operations attributable to shareholders	$	420,917		$	383,553		$	486,744
Amounts allocated to participating securities	(1,005		)	(718		)	(774		)
Net income from continuing operations attributable to common shareholders	$	419,912		$	382,835		$	485,970

Basic weighted average common shares	212,809			249,009			275,033
Potential dilutive shares	1,286			1,809			2,103
Dilutive weighted average common shares	214,095			250,818			277,136
Earnings per share from continuing operations attributable to common shareholders:
Basic	$	1.97		$	1.54		$	1.77
Diluted	1.96			1.53			1.75

Diluted earnings per share excludes the impact of shares of common stock issuable upon the lapse of certain restrictions or the exercise of options to purchase 0.3 million, 0.1 million and 0.1 million shares of stock for fiscal years 2017, 2016 and 2015, respectively, as the effect would be antidilutive.