Note 6 - Acquisitions - Unaudited Pro Forma Information (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Oct. 31, 2014		Oct. 31, 2013
Total revenues	$ 4,447,737		$ 4,187,458
Net earnings (1)	$ 100,060	[1]	$ 94,364	[1]
Earnings per common share:
Basic (in dollars per share)	$ 2.59		$ 2.46
Diluted (in dollars per share)	$ 2.56		$ 2.43

[1] Due to the revision of the financial statements described in the Form 10-K/A (Amendment No. 1) filed on December 10, 2014, Net Earnings for the six months ended October 31, 2013 have been revised.