Maximus, Inc. Annual report pursuant to Section 13 and 15(d)

Business combinations and disposals - K-12 Education (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposal									$ 0	$ 650	$ 6,880
Revenue	$ 558,446	$ 597,855	$ 612,787	$ 623,148	$ 620,903	$ 600,447	$ 622,047	$ 607,564	2,392,236	2,450,961	2,403,360
Operating income (loss)	$ 61,908	$ 82,571	$ 71,321	$ 79,683	$ 77,590	$ 81,811	$ 80,335	$ 73,776	$ 295,483	313,512	286,603
K-12 Education
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue											2,200
Operating income (loss)											(200)
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] \| Related to Disposition of K-12 Education [Member] \| K-12 Education
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposal										$ 700	$ 6,900