Summary Of Significant Accounting Policies (Property And Equipment) (Details) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Property, Plant and Equipment [Line Items]
Computer equipment	$ 113,290,000	$ 93,326,000
Office furniture and equipment	14,325,000	13,391,000
Leasehold improvements	57,976,000	54,972,000
Property and equipment, gross	185,591,000	161,689,000
Accumulated depreciation and amortization	(118,800,000)	(98,167,000)
Property and equipment, net	66,791,000	63,522,000
Depreciation and amortization expense	$ 24,700,000	$ 22,300,000	$ 19,000,000
Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	2 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years