Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Apr. 30, 2016	Apr. 30, 2015
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 57,011	$ 54,527
Allowance for loan losses	5,518	7,886
Accumulated depreciation and amortization	$ 601,120	$ 518,797
Common stock, no par value	$ 0	$ 0
Common stock, stated value per share	$ 0.01	$ 0.01
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	260,218,666	316,628,110
Treasury Stock, Shares	39,701,409.00	41,343,739
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	500,000.0	500,000.0