Condensed Consolidating Financial Statements (Balance Sheets) (Details) - USD ($) $ in Thousands	Oct. 31, 2015	Apr. 30, 2015	Oct. 31, 2014	Apr. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents	$ 360,681	$ 2,007,190	$ 627,490	$ 2,185,307
Cash and cash equivalents - restricted	42,781	91,972	55,543
Receivables, net	94,760	167,964	107,705
Deferred Tax Assets, Net, Current	145,912	174,267	197,193
Prepaid expenses and other current assets	80,458	70,283	88,270
Investments in available-for-sale securities	2,116	439,625	381,180
Total current assets	726,708	2,951,301	1,457,381
Mortgage loans held for investment, net	220,671	239,338	251,092
Property and equipment, at cost, less accumulated depreciation and amortization of $563,158, $491,153 and $518,797	298,602	311,387	318,225
Intangible assets, net	466,224	432,142	414,045
Goodwill	442,068	441,831	464,182	436,117
Deferred tax assets and income taxes receivable	11,264	13,461	37,937
Amounts due from affiliates	0	0	0
Other assets	124,360	125,960	148,428
Total assets	2,289,897	4,515,420	3,091,290
Customer banking deposits		744,241	454,860
Accounts payable and accrued expenses	141,070	231,322	97,105
Accrued salaries, wages and payroll taxes	37,512	144,744	36,215
Accrued income taxes	67,732	434,684	147,000
Current portion of long-term debt	808	790	772
Accounts payable and accrued expenses	319,426	322,508	339,725
Total current liabilities	566,548	1,878,289	1,075,677
Long-term debt	1,501,938	505,298	505,588
Deferred tax liabilities and reserves for uncertain tax positions	140,539	142,586	151,951
Deferred revenue and other noncurrent liabilities	108,115	156,298	119,398
Total liabilities	2,317,140	2,682,471	1,852,614
Stockholders’ equity	(27,243)	1,832,949	1,238,676
Total liabilities and stockholders' equity	2,289,897	4,515,420	3,091,290
Block Financial Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents	6,864	478,077	432,224	612,376
Cash and cash equivalents - restricted		45,098	5,431
Receivables, net	74,835	80,332	84,196
Deferred Tax Assets, Net, Current	82,862	77,418	101,811
Prepaid expenses and other current assets	10,046	7,771	11,760
Investments in available-for-sale securities		434,924	381,080
Total current assets	174,607	1,123,620	1,016,502
Mortgage loans held for investment, net	220,671	239,338	251,092
Property and equipment, at cost, less accumulated depreciation and amortization of $563,158, $491,153 and $518,797	186	218	157
Deferred tax assets and income taxes receivable	41,328	44,788	54,273
Amounts due from affiliates	1,334,559	134,094	10
Other assets	88,460	81,075	103,199
Total assets	1,859,811	1,623,133	1,425,233
Customer banking deposits		744,681	455,134
Accounts payable and accrued expenses	12,048	7,672	4,015
Accrued salaries, wages and payroll taxes	1,657	1,946	2,197
Accrued income taxes	51,385	49,529	47,732
Accounts payable and accrued expenses	181,519	177,063	225,247
Total current liabilities	246,609	980,891	734,325
Long-term debt	1,494,911	497,893	497,753
Deferred tax liabilities and reserves for uncertain tax positions	26,737	25,696	45,346
Deferred revenue and other noncurrent liabilities	1,204	1,783	2,131
Amounts due to affiliates			91,909
Total liabilities	1,769,461	1,506,263	1,371,464
Stockholders’ equity	90,350	116,870	53,769
Total liabilities and stockholders' equity	1,859,811	1,623,133	1,425,233
Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents	353,817	1,529,553	195,540	1,574,031
Cash and cash equivalents - restricted	42,781	46,874	50,112
Receivables, net	19,738	87,632	23,430
Deferred Tax Assets, Net, Current	63,050	96,849	95,382
Prepaid expenses and other current assets	70,412	62,512	76,510
Investments in available-for-sale securities	2,116	4,701	100
Total current assets	551,914	1,828,121	441,074
Property and equipment, at cost, less accumulated depreciation and amortization of $563,158, $491,153 and $518,797	298,416	311,169	318,068
Intangible assets, net	466,224	432,142	414,045
Goodwill	442,068	441,831	464,182
Deferred tax assets and income taxes receivable			(16,336)
Investments in subsidiaries	90,350	116,870	53,769
Amounts due from affiliates	1,128,832	1,058	92,974
Other assets	35,900	44,885	45,229
Total assets	3,013,704	3,176,076	1,813,005
Accounts payable and accrued expenses	124,717	222,546	92,147
Accrued salaries, wages and payroll taxes	35,855	142,798	34,018
Accrued income taxes	16,347	385,155	99,268
Current portion of long-term debt	808	790	772
Accounts payable and accrued expenses	137,907	145,445	114,478
Total current liabilities	315,634	896,734	340,683
Long-term debt	7,027	7,405	7,835
Deferred tax liabilities and reserves for uncertain tax positions	143,866	148,217	106,605
Deferred revenue and other noncurrent liabilities	106,911	154,515	117,267
Amounts due to affiliates	1,334,559	597,528	565,397
Total liabilities	1,907,997	1,804,399	1,137,787
Stockholders’ equity	1,105,707	1,371,677	675,218
Total liabilities and stockholders' equity	3,013,704	3,176,076	1,813,005
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Receivables, net	187		79
Total current assets	187		79
Investments in subsidiaries	1,105,707	1,371,677	675,218
Amounts due from affiliates		463,434	565,387
Total assets	1,105,894	1,835,111	1,240,684
Accounts payable and accrued expenses	4,305	1,104	943
Total current liabilities	4,305	1,104	943
Amounts due to affiliates	1,128,832	1,058	1,065
Total liabilities	1,133,137	2,162	2,008
Stockholders’ equity	(27,243)	1,832,949	1,238,676
Total liabilities and stockholders' equity	1,105,894	1,835,111	1,240,684
Intersegment Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents		(440)	(274)	$ (1,100)
Total current assets		(440)	(274)
Deferred tax assets and income taxes receivable	(30,064)	(31,327)
Investments in subsidiaries	(1,196,057)	(1,488,547)	(728,987)
Amounts due from affiliates	(2,463,391)	(598,586)	(658,371)
Other assets	0
Total assets	(3,689,512)	(2,118,900)	(1,387,632)
Customer banking deposits		(440)	(274)
Total current liabilities		(440)	(274)
Deferred tax liabilities and reserves for uncertain tax positions	(30,064)	(31,327)
Amounts due to affiliates	(2,463,391)	(598,586)	(658,371)
Total liabilities	(2,493,455)	(630,353)	(658,645)
Stockholders’ equity	(1,196,057)	(1,488,547)	(728,987)
Total liabilities and stockholders' equity	$ (3,689,512)	$ (2,118,900)	$ (1,387,632)