Reportable Segments - Financial Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2019 USD ($)	Jul. 01, 2018 USD ($)	Jun. 30, 2019 USD ($) segment	Jul. 01, 2018 USD ($)	Sep. 30, 2018 USD ($)
Financial information regarding reportable segments
Number of reportable segments \| segment			2
Revenue	$ 825,793	$ 764,795	$ 2,265,846	$ 2,224,805
Income from operations	64,841	55,496	168,097	146,801
Total Assets	2,096,423		2,096,423		$ 1,959,421
Operating segment \| GSG
Financial information regarding reportable segments
Revenue	491,989	423,912	1,321,486	1,272,712
Income from operations	52,487	44,372	134,704	117,674
Total Assets	629,594		629,594		468,010
Operating segment \| CIG
Financial information regarding reportable segments
Revenue	347,757	352,631	988,009	993,849
Income from operations	27,025	27,892	74,994	67,585
Total Assets	447,761		447,761		478,197
Operating segment \| RCM
Financial information regarding reportable segments
Revenue	329	3,336	(2,862)	11,622
Income from operations	3	(485)	(5,931)	(2,132)
Total Assets	15,886		15,886		25,683
Elimination of inter-segment revenue
Financial information regarding reportable segments
Revenue	(14,282)	(15,084)	(40,787)	(53,378)
Corporate
Financial information regarding reportable segments
Income from operations	(14,674)	$ (16,283)	(35,670)	$ (36,326)
Total Assets	$ 1,003,182		$ 1,003,182		$ 987,531

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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