Goodwill and Acquired Intangible Assets (Schedule Of Movements of Goodwill by Reportable Segment) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	12 Months Ended
	Sep. 30, 2016	Apr. 02, 2016	Jan. 02, 2016	Apr. 02, 2016	Sep. 30, 2016	Sep. 30, 2015
Goodwill [Roll Forward]
Balance, beginning of period	$ 1,169,660		$ 1,069,041	$ 1,069,041	$ 1,069,041	$ 1,012,527
Foreign currency translation and other adjustments	153			222		(28,594)
Balance, end of period	1,169,813				1,169,813	1,069,041
Software Products [Member]
Goodwill [Roll Forward]
Balance, beginning of period	1,117,038		1,016,413	1,016,413	1,016,413	959,768
Foreign currency translation and other adjustments				228		(28,463)
Balance, end of period						1,016,413
Services [Member]
Goodwill [Roll Forward]
Balance, beginning of period	52,622		52,628	52,628	52,628	52,759
Foreign currency translation and other adjustments				$ (6)		(131)
Balance, end of period						52,628
Solutions Group [Member]
Goodwill [Roll Forward]
Balance, beginning of period	1,050,013
Foreign currency translation and other adjustments	137
Balance, end of period	1,050,150				1,050,150
Technology Platform Group [Member]
Goodwill [Roll Forward]
Balance, beginning of period	90,053
Foreign currency translation and other adjustments	12
Balance, end of period	90,065				90,065
Professional Services [Member]
Goodwill [Roll Forward]
Balance, beginning of period	29,594
Foreign currency translation and other adjustments	4
Balance, end of period	$ 29,598				29,598
Acquired entity name: Axeda [Member]
Goodwill [Roll Forward]
Adjustment of purchase price from escrow						(180)
Acquired entity name: Axeda [Member] | Software Products [Member]
Goodwill [Roll Forward]
Adjustment of purchase price from escrow						(180)
Acquired entity name: Axeda [Member] | Services [Member]
Goodwill [Roll Forward]
Adjustment of purchase price from escrow						0
Acquired entity name: ColdLight [Member]
Goodwill [Roll Forward]
Goodwill acquired						85,288
Acquired entity name: ColdLight [Member] | Software Products [Member]
Goodwill [Roll Forward]
Goodwill acquired						85,288
Acquired entity name: ColdLight [Member] | Services [Member]
Goodwill [Roll Forward]
Goodwill acquired						$ 0
Vuforia Acquisition [Member]
Goodwill [Roll Forward]
Goodwill acquired			23,316
Vuforia Acquisition [Member] | Software Products [Member]
Goodwill [Roll Forward]
Goodwill acquired			23,316
Vuforia Acquisition [Member] | Services [Member]
Goodwill [Roll Forward]
Goodwill acquired			$ 0
Acquired entity name: Kepware [Member]
Goodwill [Roll Forward]
Goodwill acquired		$ 77,081			$ 77,081
Acquired entity name: Kepware [Member] | Software Products [Member]
Goodwill [Roll Forward]
Goodwill acquired		77,081
Acquired entity name: Kepware [Member] | Services [Member]
Goodwill [Roll Forward]
Goodwill acquired		$ 0