Segment Information (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013
Segment Reporting Information [Line Items]
Total revenues	$ 2,301,370us-gaap_Revenues	$ 509,074us-gaap_Revenues	$ 134,628us-gaap_Revenues	$ 133,586us-gaap_Revenues	$ 2,562,990us-gaap_Revenues	$ 199,770us-gaap_Revenues	$ 134,340us-gaap_Revenues	$ 127,195us-gaap_Revenues	$ 3,078,658us-gaap_Revenues	$ 3,024,295us-gaap_Revenues	$ 2,905,943us-gaap_Revenues
Assets	4,515,420us-gaap_Assets				4,693,529us-gaap_Assets				4,515,420us-gaap_Assets	4,693,529us-gaap_Assets	4,537,779us-gaap_Assets
Foreign
Segment Reporting Information [Line Items]
Total revenues									231,700	232,200	249,000
Assets	$ 284,500				$ 303,900				$ 284,500	$ 303,900	$ 472,600