Acquisition (Business Combination) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013	May. 07, 2015
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Acquisition-related cost	$ 8,900	$ 12,700	$ 9,900
Payments to Acquire Businesses, Net of Cash Acquired	98,411	323,525	245,843
Borrowings under credit facility	185,000	1,386,250	$ 0
Credit facility, borrowings outstanding	668,100
Acquired entity name: ColdLight [Member]
Acquired entity Name
Goodwill, Acquired During Period	85,288
Finite-lived Intangible Assets Acquired	17,620
Business Combination, Contingent Consideration Arrangements, Change in Range of Outcomes, Contingent Consideration, Liability, Value, Low	3,800
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Payments to Acquire Businesses, Net of Cash Acquired	98,592
Cash Acquired from Acquisition	1,313
Business Combination, Consideration Transferred	102,392
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High				$ 5,000
Contingent consideration	4,000			$ 3,800
Increase in estimated fair value of liability	200	0
Business acquisition, acquired net assets excluding goodwill, intangible assets and cash	(516)
acquired entity name-ThingWorx [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Increase in estimated fair value of liability	$ 2,809	$ 2,143
Computer Software, Intangible Asset [Member]
Acquired entity Name
Weighted average useful lives of acquired intangible assets	9 years
Computer Software, Intangible Asset [Member] | Acquired entity name: ColdLight [Member]
Acquired entity Name
Finite-lived Intangible Assets Acquired	$ 13,600
Weighted average useful lives of acquired intangible assets	10 years
Customer Lists [Member]
Acquired entity Name
Weighted average useful lives of acquired intangible assets	10 years
Customer Lists [Member] | Acquired entity name: ColdLight [Member]
Acquired entity Name
Finite-lived Intangible Assets Acquired	$ 3,500
Weighted average useful lives of acquired intangible assets	9 years
Trademarks and Trade Names [Member] | Acquired entity name: ColdLight [Member]
Acquired entity Name
Finite-lived Intangible Assets Acquired	$ 500
Weighted average useful lives of acquired intangible assets	7 years
Number of Employees, Total [Member] | Acquired entity name: ColdLight [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Business Acquisition, Description of Acquired Entity, Number of Employee Acquired	60
Line of Credit [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Credit facility, borrowings outstanding	$ 193,100
Revolving Loan, Reset October 6, 2015 | Line of Credit [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Credit facility, borrowings outstanding	$ 100,000