Reportable Segments - Financial Information (Details) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2019 USD ($)	Apr. 01, 2018 USD ($)	Mar. 31, 2019 USD ($) segment	Apr. 01, 2018 USD ($)	Sep. 30, 2018 USD ($)
Financial information regarding reportable segments
Number of reportable segments \| segment			2
Revenue	$ 722,621	$ 700,262	$ 1,440,052	$ 1,460,010
Income from operations	47,545	42,716	103,256	91,305
Total Assets	1,951,865		1,951,865		$ 1,959,421
Operating segment \| GSG
Financial information regarding reportable segments
Revenue	417,526	406,027	829,497	848,799
Income from operations	44,803	34,177	82,217	73,302
Total Assets	524,796		524,796		468,010
Operating segment \| CIG
Financial information regarding reportable segments
Revenue	322,458	309,704	640,252	641,217
Income from operations	20,869	18,400	47,968	39,693
Total Assets	410,918		410,918		478,197
Operating segment \| RCM
Financial information regarding reportable segments
Revenue	(4,645)	1,480	(3,192)	8,286
Income from operations	(5,938)	(489)	(5,934)	(1,647)
Total Assets	17,213		17,213		25,683
Elimination of inter-segment revenue
Financial information regarding reportable segments
Revenue	(12,718)	(16,949)	(26,505)	(38,292)
Corporate
Financial information regarding reportable segments
Income from operations	(12,189)	$ (9,372)	(20,995)	$ (20,043)
Total Assets	$ 998,938		$ 998,938		$ 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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