Condensed Consolidating Financial Statements (Cash Flows) (Details) - USD ($) $ in Thousands	6 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Apr. 30, 2015	Apr. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities:	$ (602,713)	$ (627,577)
Sales, maturities of and payments received on AFS securities	434,261	49,013
Principal payments on mortgage loans held for investment, net	17,006	13,451
Capital expenditures	(38,779)	(70,927)
Payments made for business acquisitions, net of cash acquired	(61,846)	(94,230)
Loans made to franchisees	(10,281)	(18,251)
Repayments from franchisees	17,473	29,637
Other, net	7,246	10,585
Net cash provided by (used in) investing activities	365,080	(80,722)
Repayments of long-term debt	0	(400,000)
Proceeds from issuance of long-term debt	996,831	0
Customer banking deposits, net	(326,705)	(316,269)
Transfer of bank deposits	(419,028)	0
Dividends paid	(110,338)	(109,871)
Repurchase of common stock, including shares surrendered	(1,517,786)	(10,247)
Proceeds from exercise of stock options	16,875	14,477
Other, net	(37,820)	(23,392)
Net cash used in financing activities	(1,397,971)	(845,302)
Effects of exchange rates on cash	(10,905)	(4,216)
Net decrease in cash and cash equivalents	(1,646,509)	(1,557,817)
Cash & cash equivalents	360,681	627,490	$ 2,007,190	$ 2,185,307
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Dividends paid	(110,338)	(109,871)
Repurchase of common stock, including shares surrendered	(1,517,786)	(10,247)
Proceeds from exercise of stock options	16,875	14,477
Intercompany borrowings	1,611,564	105,641
Other, net	(315)
Block Financial Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities:	36,078	55,612
Sales, maturities of and payments received on AFS securities	430,460	49,013
Principal payments on mortgage loans held for investment, net	17,006	13,451
Capital expenditures	(20)	(119)
Loans made to franchisees	(10,206)	(18,180)
Repayments from franchisees	17,301	29,404
Intercompany payments/investments in subsidiaries	(1,200,465)	400,000
Other, net	4,854	4,372
Net cash provided by (used in) investing activities	(741,070)	477,941
Repayments of long-term debt		(400,000)
Proceeds from issuance of long-term debt	996,831
Customer banking deposits, net	(327,145)	(317,095)
Transfer of bank deposits	(419,028)
Intercompany borrowings		3,390
Other, net	(16,879)
Net cash used in financing activities	233,779	(713,705)
Net decrease in cash and cash equivalents	(471,213)	(180,152)
Cash & cash equivalents	6,864	432,224	478,077	612,376
Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities:	(638,791)	(683,189)
Sales, maturities of and payments received on AFS securities	3,801
Capital expenditures	(38,759)	(70,808)
Payments made for business acquisitions, net of cash acquired	(61,846)	(94,230)
Loans made to franchisees	(75)	(71)
Repayments from franchisees	172	233
Intercompany payments/investments in subsidiaries	(1,611,564)	(109,031)
Other, net	2,392	6,213
Net cash provided by (used in) investing activities	(1,705,879)	(267,694)
Intercompany borrowings	1,200,465	(400,000)
Other, net	(20,626)	(23,392)
Net cash used in financing activities	1,179,839	(423,392)
Effects of exchange rates on cash	(10,905)	(4,216)
Net decrease in cash and cash equivalents	(1,175,736)	(1,378,491)
Cash & cash equivalents	353,817	195,540	1,529,553	1,574,031
Intersegment Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Intercompany payments/investments in subsidiaries	2,812,029	(290,969)
Net cash provided by (used in) investing activities	2,812,029	(290,969)
Customer banking deposits, net	440	826
Intercompany borrowings	(2,812,029)	290,969
Net cash used in financing activities	(2,811,589)	291,795
Net decrease in cash and cash equivalents	$ 440	826
Cash & cash equivalents		$ (274)	$ (440)	$ (1,100)