Condensed Consolidating Financial Statements (Balance Sheets) (Details) - USD ($) $ in Thousands	Jul. 31, 2016	Apr. 30, 2016	Jul. 31, 2015	Apr. 30, 2015
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents	$ 306,871	$ 896,801	$ 1,299,382	$ 2,007,190
Cash and cash equivalents - restricted	122,025	104,110	61,040
Receivables, net	103,425	153,116	103,194
Deferred Tax Assets, Net, Current			160,390
Prepaid expenses and other current assets	74,929	65,441	80,550
Investments in available-for-sale securities	1,123	1,133	406,360
Total current assets	608,373	1,220,601	2,110,916
Mortgage loans held for investment, net	192,375	202,385	230,130
Property and equipment, at cost, less accumulated depreciation and amortization of $622,937, $538,823 and $601,120	284,114	293,565	297,321
Intangible assets, net	419,909	433,885	417,009
Goodwill	470,942	470,757	454,394	441,831
Deferred tax assets and income taxes receivable	90,498	120,123	11,377
Amounts due from affiliates	0	0	0
Other assets	97,331	105,909	108,307
Total assets	2,163,542	2,847,225	3,629,454
Customer banking deposits			476,732
Accounts payable and accrued expenses	157,085	259,586	116,855
Accrued salaries, wages and payroll taxes	43,516	161,786	33,447
Accrued income taxes and reserves for uncertain tax positions	216,390	373,754	245,541
Current portion of long-term debt	864	826	799
Accounts payable and accrued expenses	191,304	243,653	316,880
Total current liabilities	609,159	1,039,605	1,190,254
Long-term debt	1,491,790	1,491,375	501,960
Deferred tax liabilities and reserves for uncertain tax positions	116,709	132,960	137,603
Deferred revenue and other noncurrent liabilities	145,691	160,182	130,210
Total liabilities	2,363,349	2,824,122	1,960,027
Stockholders’ equity	(199,807)	23,103	1,669,427
Total liabilities and stockholders' equity	2,163,542	2,847,225	3,629,454
Block Financial Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents	3,902	9,025	286,165	478,077
Cash and cash equivalents - restricted	29,000	29,004	11,806
Receivables, net	72,865	71,882	77,539
Deferred Tax Assets, Net, Current			78,184
Prepaid expenses and other current assets	7,114	6,925	6,374
Investments in available-for-sale securities			404,221
Total current assets	112,881	116,836	864,289
Mortgage loans held for investment, net	192,375	202,385	230,130
Property and equipment, at cost, less accumulated depreciation and amortization of $622,937, $538,823 and $601,120	116	136	210
Deferred tax assets and income taxes receivable	60,312	77,270	41,328
Amounts due from affiliates	1,282,286	1,307,612	131,889
Other assets	58,311	62,806	69,215
Total assets	1,706,281	1,767,045	1,337,061
Customer banking deposits			477,222
Accounts payable and accrued expenses	7,671	18,596	6,679
Accrued salaries, wages and payroll taxes	1,889	1,766	2,293
Accrued income taxes and reserves for uncertain tax positions	52,976	52,976	49,240
Accounts payable and accrued expenses	52,420	87,982	169,900
Total current liabilities	114,956	161,320	705,334
Long-term debt	1,485,426	1,484,766	494,727
Deferred tax liabilities and reserves for uncertain tax positions	8,577	10,786	26,737
Deferred revenue and other noncurrent liabilities	1,106	1,178	1,660
Amounts due to affiliates			21
Total liabilities	1,610,065	1,658,050	1,228,479
Stockholders’ equity	96,216	108,995	108,582
Total liabilities and stockholders' equity	1,706,281	1,767,045	1,337,061
Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents	302,969	887,776	1,013,707	1,529,553
Cash and cash equivalents - restricted	93,025	75,106	49,234
Receivables, net	30,560	81,234	25,654
Deferred Tax Assets, Net, Current			82,206
Prepaid expenses and other current assets	67,815	58,516	74,176
Investments in available-for-sale securities	1,123	1,133	2,139
Total current assets	495,492	1,103,765	1,247,116
Property and equipment, at cost, less accumulated depreciation and amortization of $622,937, $538,823 and $601,120	283,998	293,429	297,111
Intangible assets, net	419,909	433,885	417,009
Goodwill	470,942	470,757	454,394
Deferred tax assets and income taxes receivable	30,186	36,936
Investments in subsidiaries	96,216	108,995	108,582
Amounts due from affiliates	1,794,655	1,714,009	1,423
Other assets	39,020	43,103	39,092
Total assets	3,630,418	4,204,879	2,564,727
Accounts payable and accrued expenses	138,863	239,459	108,970
Accrued salaries, wages and payroll taxes	41,627	160,020	31,154
Accrued income taxes and reserves for uncertain tax positions	163,414	320,778	196,301
Current portion of long-term debt	864	826	799
Accounts payable and accrued expenses	138,884	155,671	146,980
Total current liabilities	483,652	876,754	484,204
Long-term debt	6,364	6,609	7,233
Deferred tax liabilities and reserves for uncertain tax positions	101,644	116,257	140,817
Deferred revenue and other noncurrent liabilities	144,585	159,004	128,550
Amounts due to affiliates	1,282,286	1,307,612	544,813
Total liabilities	2,018,531	2,466,236	1,305,617
Stockholders’ equity	1,611,887	1,738,643	1,259,110
Total liabilities and stockholders' equity	3,630,418	4,204,879	2,564,727
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Receivables, net			1
Total current assets			1
Deferred tax assets and income taxes receivable		5,917
Investments in subsidiaries	1,611,887	1,738,643	1,259,110
Amounts due from affiliates		0	412,924
Total assets	1,611,887	1,744,560	1,672,035
Accounts payable and accrued expenses	10,551	1,531	1,206
Total current liabilities	10,551	1,531	1,206
Deferred tax liabilities and reserves for uncertain tax positions	6,488	5,917
Amounts due to affiliates	1,794,655	1,714,009	1,402
Total liabilities	1,811,694	1,721,457	2,608
Stockholders’ equity	(199,807)	23,103	1,669,427
Total liabilities and stockholders' equity	1,611,887	1,744,560	1,672,035
Intersegment Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents			(490)	$ (440)
Total current assets			(490)
Deferred tax assets and income taxes receivable			(29,951)
Investments in subsidiaries	(1,708,103)	(1,847,638)	(1,367,692)
Amounts due from affiliates	(3,076,941)	(3,021,621)	(546,236)
Other assets	0
Total assets	(4,785,044)	(4,869,259)	(1,944,369)
Customer banking deposits			(490)
Total current liabilities			(490)
Deferred tax liabilities and reserves for uncertain tax positions			(29,951)
Amounts due to affiliates	(3,076,941)	(3,021,621)	(546,236)
Total liabilities	(3,076,941)	(3,021,621)	(576,677)
Stockholders’ equity	(1,708,103)	(1,847,638)	(1,367,692)
Total liabilities and stockholders' equity	$ (4,785,044)	$ (4,869,259)	$ (1,944,369)