Earnings Per Common Share (Tables)

12 Months Ended

Apr. 30, 2012

Earnings Per Common Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

		Years ended April 30,
		2012		2011		2010
Basic
Net earnings	$	116,791	$	94,623	$	116,962
Weighted average shares outstanding-basic		38,068,001		42,284,664		50,899,370
Basic earnings per common share	$	3.07	$	2.24	$	2.30
Diluted
Net earnings	$	116,791	$	94,623	$	116,962
Weighted-average shares outstanding-basic		38,068,001		42,284,664		50,899,370
Plus effect of stock options and restricted stock units		323,703		281,913		153,803
Weighted-average shares outstanding-diluted		38,391,704		42,566,577		51,053,173
Diluted earnings per common share	$	3.04	$	2.22	$	2.29