Fair Value (Summary Of Carrying Amounts And Estimated Fair Values Of Company's Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified					9 Months Ended	12 Months Ended					9 Months Ended	12 Months Ended
	Jan. 31, 2013	Apr. 30, 2012	Jan. 31, 2012	Apr. 30, 2011	Jan. 31, 2013 Level 1 [Member]	Apr. 30, 2012 Level 1 [Member]	Jan. 31, 2013 Level 2 [Member]	Apr. 30, 2012 Level 2 [Member]	Jan. 31, 2013 Level 3 [Member]	Apr. 30, 2012 Level 3 [Member]	Jan. 31, 2013 Level 1 And 3 [Member]	Apr. 30, 2012 Level 1 And 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, Carrying Amount	$ 418,385	$ 1,944,334	$ 1,218,984	$ 1,677,844	$ 418,385	$ 1,944,334
Cash and cash equivalents, Estimated Fair Value					418,385	1,944,334
Cash and cash equivalents - restricted, Carrying Amount	37,958	48,100			37,958	48,100
Cash and cash equivalents - restricted, Estimated Fair Value					37,958	48,100
Receivables, net	949,160	193,858	1,035,902		949,160	193,858
Receivables, net - short-term, Estimated Fair Value					949,160	193,858
Mortgage loans held for investment	357,887	406,201							357,887	406,201
Mortgage loans held for investment, net, Estimated Fair Value									217,019	248,535
Investments in available-for-sale securities, Carrying Amount	396,312	371,315					397,313	372,352
Investments in available-for-sale securities, Fair Value	397,313	372,352					397,313	372,352
Receivables, net - long-term, Carrying Amount											158,228	127,468
Receivables, net - long-term, Estimated Fair Value											158,228	127,468
Note receivable (including interest), Carrying Amount									59,213	55,444
Note receivable (including interest), Estimated Fair Value									67,048	55,444
Customer deposits	1,036,968	827,549									1,041,942	833,047
Deposits, Estimated Fair Value											1,042,282	831,251
Long-term debt, Carrying Amount	906,012	409,115	409,241						906,725	1,040,549
Long-term debt, Estimated Fair Value									$ 946,793	$ 1,077,223