Acquisitions Acquisitions (Purchase Price Allocation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Business Acquisition [Line Items]
Net cash used to acquire	$ 98,411	$ 323,525	$ 245,843
Acquired entity name: ColdLight [Member]
Business Acquisition [Line Items]
Goodwill	85,288
Identifiable intangible assets	17,620
Cash	1,313
Other assets and liabilities, net	(516)
Total allocation of purchase price consideration	103,705
Less: cash acquired	(1,313)
Total purchase price allocation, net of cash acquired	102,392
Less: contingent consideration	(3,800)
Net cash used to acquire	$ 98,592