Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Nov. 30, 2011	Nov. 30, 2010	Nov. 30, 2011	Nov. 30, 2010
Segment Reporting Information [Line Items]
Number of reportable segments	2		2
Revenues [Abstract]
Revenue, net	$ 530,505	$ 443,526	$ 1,073,276	$ 883,665
Operating income	96,580	83,143	205,190	165,251
Depreciation and amortization	24,024	18,024	48,240	34,728
North America merchant services [Member]
Revenues [Abstract]
Revenue, net	378,937	327,124	757,583	663,968
Operating income	70,673	67,131	142,431	135,499
Depreciation and amortization	8,535	8,249	17,067	15,913
North America merchant services [Member] | UNITED STATES
Revenues [Abstract]
Revenue, net	293,416	245,671	580,841	501,302
North America merchant services [Member] | CANADA
Revenues [Abstract]
Revenue, net	85,521	81,453	176,742	162,666
International merchant services [Member]
Revenues [Abstract]
Revenue, net	151,568	116,402	315,693	219,697
Operating income	44,494	35,349	100,152	66,742
Depreciation and amortization	14,720	9,371	29,880	18,290
International merchant services [Member] | Europe
Revenues [Abstract]
Revenue, net	115,169	79,881	244,583	153,677
International merchant services [Member] | Asia-Pacific
Revenues [Abstract]
Revenue, net	36,399	36,521	71,110	66,020
Corporation [Member]
Revenues [Abstract]
Operating income	(18,587)	(19,337)	(37,393)	(36,990)
Depreciation and amortization	$ 769	$ 404	$ 1,293	$ 525