Goodwill and Intangible Assets (Schedule of Goodwill) (Details) $ in Thousands	6 Months Ended
Mar. 31, 2018 USD ($)
Goodwill [Line Items]
Balance, October 1, 2017	$ 1,182,772
Acquisition	4,350
Foreign currency translation adjustment	4,481
Balance, March 31, 2018	1,191,603
Software Products
Goodwill [Line Items]
Balance, October 1, 2017	1,152,917
Acquisition	4,350
Foreign currency translation adjustment	4,368
Balance, March 31, 2018	1,161,635
Professional Services
Goodwill [Line Items]
Balance, October 1, 2017	29,855
Acquisition	0
Foreign currency translation adjustment	113
Balance, March 31, 2018	$ 29,968

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

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