Condensed Consolidating Financial Statements (Balance Sheets) (Details) - USD ($) $ in Thousands	Jan. 31, 2017	Apr. 30, 2016	Jan. 31, 2016	Apr. 30, 2015
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents	$ 221,172	$ 896,801	$ 189,511	$ 2,007,190
Cash and cash equivalents - restricted	70,166	104,110	69,649
Receivables, net	787,865	153,116	829,774
Deferred Tax Assets, Net, Current	38,032		29,411
Prepaid expenses and other current assets	85,599	66,574	100,504
Total current assets	1,202,834	1,220,601	1,218,849
Mortgage loans held for investment, net		202,385	212,106
Property and equipment, at cost, less accumulated depreciation and amortization of $673,594, $585,419 and $601,120	282,358	293,565	290,202
Intangible assets, net	434,720	433,885	473,732
Goodwill	483,320	470,757	443,418	441,831
Deferred tax assets and income taxes receivable	71,639	120,123	113,887
Amounts due from affiliates	0	0	0
Other assets	102,760	105,909	110,742
Total assets	2,577,631	2,847,225	2,862,936
Accounts payable and accrued expenses	239,085	259,586	205,981
Accrued salaries, wages and payroll taxes	123,457	161,786	123,289
Accrued income taxes and reserves for uncertain tax positions	7,537	373,754	8,099
Current portion of long-term debt	942	826	817
Deferred revenue and other current liabilities	183,616	243,653	250,846
Total current liabilities	554,637	1,039,605	589,032
Long-term debt and line of credit borrowings	2,592,622	1,491,375	2,615,823
Deferred tax liabilities and reserves for uncertain tax positions	109,557	132,960	88,377
Deferred revenue and other noncurrent liabilities	121,631	160,182	106,438
Total liabilities	3,378,447	2,824,122	3,399,670
Stockholders’ equity	(800,816)	23,103	(536,734)
Total liabilities and stockholders' equity	2,577,631	2,847,225	2,862,936
Block Financial Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents	4,272	9,025	10,415	478,077
Cash and cash equivalents - restricted	8,052	29,004	29,000
Receivables, net	422,034	71,882	446,367
Prepaid expenses and other current assets	3,217	6,925	8,800
Total current assets	437,575	116,836	494,582
Mortgage loans held for investment, net		202,385	212,106
Property and equipment, at cost, less accumulated depreciation and amortization of $673,594, $585,419 and $601,120	81	136	160
Deferred tax assets and income taxes receivable	54,777	77,270	60,588
Amounts due from affiliates	2,168,620	1,307,612	2,045,204
Other assets	67,619	62,806	76,979
Total assets	2,728,672	1,767,045	2,889,619
Accounts payable and accrued expenses	15,051	18,596	12,466
Accrued salaries, wages and payroll taxes	461	1,766	1,515
Accrued income taxes and reserves for uncertain tax positions		52,976	54,227
Deferred revenue and other current liabilities	33,872	87,982	98,490
Total current liabilities	49,384	161,320	166,698
Long-term debt and line of credit borrowings	2,586,744	1,484,766	2,609,003
Deferred tax liabilities and reserves for uncertain tax positions	10,786	10,786	6,814
Deferred revenue and other noncurrent liabilities	1,059	1,178	1,161
Total liabilities	2,647,973	1,658,050	2,783,676
Stockholders’ equity	80,699	108,995	105,943
Total liabilities and stockholders' equity	2,728,672	1,767,045	2,889,619
Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents	216,900	887,776	179,096	1,529,553
Cash and cash equivalents - restricted	62,114	75,106	40,649
Receivables, net	365,831	81,234	383,406
Deferred Tax Assets, Net, Current	38,032		79,631
Prepaid expenses and other current assets	82,382	59,649	91,704
Total current assets	765,259	1,103,765	774,486
Property and equipment, at cost, less accumulated depreciation and amortization of $673,594, $585,419 and $601,120	282,277	293,429	290,042
Intangible assets, net	434,720	433,885	473,732
Goodwill	483,320	470,757	443,418
Deferred tax assets and income taxes receivable	13,532	36,936	49,563
Investments in subsidiaries	80,699	108,995	105,943
Amounts due from affiliates	2,166,873	1,714,009	1,535,377
Other assets	35,141	43,103	33,763
Total assets	4,261,821	4,204,879	3,706,324
Accounts payable and accrued expenses	222,093	239,459	169,932
Accrued salaries, wages and payroll taxes	122,996	160,020	121,774
Accrued income taxes and reserves for uncertain tax positions	7,537	320,778
Current portion of long-term debt	942	826	817
Deferred revenue and other current liabilities	149,744	155,671	152,356
Total current liabilities	503,312	876,754	444,879
Long-term debt and line of credit borrowings	5,878	6,609	6,820
Deferred tax liabilities and reserves for uncertain tax positions	92,854	116,257	79,302
Deferred revenue and other noncurrent liabilities	120,572	159,004	105,277
Amounts due to affiliates	2,168,620	1,307,612	2,045,204
Total liabilities	2,891,236	2,466,236	2,681,482
Stockholders’ equity	1,370,585	1,738,643	1,024,842
Total liabilities and stockholders' equity	4,261,821	4,204,879	3,706,324
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Receivables, net			1
Total current assets			1
Deferred tax assets and income taxes receivable	3,330	5,917	3,736
Investments in subsidiaries	1,370,585	1,738,643	1,024,842
Amounts due from affiliates		0	0
Total assets	1,373,915	1,744,560	1,028,579
Accounts payable and accrued expenses	1,941	1,531	23,583
Accrued income taxes and reserves for uncertain tax positions			4,092
Total current liabilities	1,941	1,531	27,675
Deferred tax liabilities and reserves for uncertain tax positions	5,917	5,917	2,261
Amounts due to affiliates	2,166,873	1,714,009	1,535,377
Total liabilities	2,174,731	1,721,457	1,565,313
Stockholders’ equity	(800,816)	23,103	(536,734)
Total liabilities and stockholders' equity	1,373,915	1,744,560	1,028,579
Intersegment Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Cash & cash equivalents				$ (440)
Deferred Tax Assets, Net, Current			(50,220)
Total current assets			(50,220)
Investments in subsidiaries	(1,451,284)	(1,847,638)	(1,130,785)
Amounts due from affiliates	(4,335,493)	(3,021,621)	(3,580,581)
Other assets	0
Total assets	(5,786,777)	(4,869,259)	(4,761,586)
Accrued income taxes and reserves for uncertain tax positions			(50,220)
Total current liabilities			(50,220)
Amounts due to affiliates	(4,335,493)	(3,021,621)	(3,580,581)
Total liabilities	(4,335,493)	(3,021,621)	(3,630,801)
Stockholders’ equity	(1,451,284)	(1,847,638)	(1,130,785)
Total liabilities and stockholders' equity	$ (5,786,777)	$ (4,869,259)	$ (4,761,586)