Condensed Consolidating Financial Statements (Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Apr. 30, 2015	Apr. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities:	$ (378,246)	$ (381,585)
Maturities of and payments received on AFS securities	32,103	18,484
Principal payments on mortgage loans held for investment, net	8,537	6,250
Capital expenditures	(8,689)	(25,841)
Payments made for business acquisitions, net of cash acquired	(12,271)	(40,533)
Loans made to franchisees	(2,582)	(7,398)
Repayments from franchisees	11,434	18,674
Other, net	3,562	4,030
Net cash provided by (used in) investing activities	32,094	(26,334)
Customer banking deposits, net	(268,532)	(287,609)
Dividends paid	(55,063)	(54,852)
Payments for repurchase of common stock, including shares surrendered	17,756	9,397
Proceeds from exercise of stock options	13,015	13,368
Other, net	(22,413)	(9,919)
Net cash used in financing activities	(350,749)	(348,409)
Effects of exchange rates on cash	(10,907)	510
Net decrease in cash and cash equivalents	(707,808)	(755,818)
Cash & cash equivalents	1,299,382	1,429,489	$ 2,007,190	$ 2,185,307
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Dividends paid	(55,063)	(54,852)
Payments for repurchase of common stock, including shares surrendered	17,756	9,397
Proceeds from exercise of stock options	13,015	13,368
Intercompany borrowings	59,804	50,881
Block Financial Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities:	27,342	(20,669)
Maturities of and payments received on AFS securities	28,339	18,484
Principal payments on mortgage loans held for investment, net	8,537	6,250
Capital expenditures	(19)	(116)
Loans made to franchisees	(2,582)	(7,398)
Repayments from franchisees	11,288	18,674
Intercompany payments/investments in subsidiaries	2,226	64,322
Other, net	1,439	1,868
Net cash provided by (used in) investing activities	49,228	102,084
Customer banking deposits, net	(268,482)	(288,279)
Net cash used in financing activities	(268,482)	(288,279)
Net decrease in cash and cash equivalents	(191,912)	(206,864)
Cash & cash equivalents	286,165	405,512	478,077	612,376
Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities:	(405,588)	(360,916)
Maturities of and payments received on AFS securities	3,764
Capital expenditures	(8,670)	(25,725)
Payments made for business acquisitions, net of cash acquired	(12,271)	(40,533)
Repayments from franchisees	146
Intercompany payments/investments in subsidiaries	(59,804)	(50,881)
Other, net	2,123	2,162
Net cash provided by (used in) investing activities	(74,712)	(114,977)
Intercompany borrowings	(2,226)	(64,322)
Other, net	(22,413)	(9,919)
Net cash used in financing activities	(24,639)	(74,241)
Effects of exchange rates on cash	(10,907)	510
Net decrease in cash and cash equivalents	(515,846)	(549,624)
Cash & cash equivalents	1,013,707	1,024,407	1,529,553	1,574,031
Intersegment Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Intercompany payments/investments in subsidiaries	57,578	(13,441)
Net cash provided by (used in) investing activities	57,578	(13,441)
Customer banking deposits, net	(50)	670
Intercompany borrowings	(57,578)	13,441
Net cash used in financing activities	(57,628)	14,111
Net decrease in cash and cash equivalents	(50)	670
Cash & cash equivalents	$ (490)	$ (430)	$ (440)	$ (1,100)