Quarterly information (unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Revenue	$ 578,683	$ 572,301	$ 481,794	$ 467,043	$ 435,406	$ 419,899	$ 439,015	$ 406,592	$ 2,099,821	$ 1,700,912	$ 1,331,279
Gross profit	125,307	143,798	124,345	119,267	112,932	112,603	120,672	105,916	512,717	452,123	386,033
Amortization of intangible assets	(3,166)	(3,275)	(1,432)	(1,475)	(1,527)	(1,542)	(1,468)	(1,353)	(9,348)	(5,890)	(4,883)
Selling, general and administrative expenses									(238,792)	(220,925)	(193,827)
Acquisition-related expenses	(172)	(2,459)	(1,514)	(600)					(4,745)		(2,168)
Operating income	61,527	71,067	62,007	65,231	51,808	55,223	64,980	53,297	259,832	225,308	185,155
Net income	36,412	42,259	39,028	42,350	36,152	34,428	41,461	33,355	160,049	145,396	117,349
Net income attributable to MAXIMUS	$ 35,437	$ 41,666	$ 38,808	$ 41,861	$ 36,236	$ 34,138	$ 41,207	$ 33,859	$ 157,772	$ 145,440	$ 116,731
Diluted earnings per share attributable to Maximus (in dollars per share)	$ 0.53	$ 0.62	$ 0.58	$ 0.63	$ 0.53	$ 0.49	$ 0.59	$ 0.49	$ 2.35	$ 2.11	$ 1.67
Other/Corporate
Selling, general and administrative expenses	$ 102	$ (8)	$ (95)	$ (5)	$ 1	$ (35)	$ (563)	$ (17)
Health Services \| Operating segments
Revenue	296,201	298,549	270,918	243,570	230,450	228,703	230,953	216,544	$ 1,109,238	$ 906,650	$ 691,565
Gross profit	54,575	69,813	69,873	59,847	59,018	54,900	51,616	48,194	254,108	213,728	172,336
Selling, general and administrative expenses	(30,507)	(44,470)	(41,476)	(37,840)	(31,150)	(29,153)	(29,709)	(25,544)	(99,815)	(98,172)	(83,131)
Operating income									154,293	115,556	89,205
U.S. Federal Services \| Operating segments
Revenue	154,279	141,011	99,465	107,729	90,605	76,550	92,645	82,040	502,484	341,840	167,258
Gross profit	36,284	34,780	22,014	25,568	24,597	24,632	33,252	28,312	118,646	110,793	73,694
Selling, general and administrative expenses	(20,903)	(15,536)	(9,637)	(13,318)	(12,239)	(14,046)	(20,026)	(16,787)	(59,252)	(47,695)	(31,128)
Operating income									59,394	63,098	42,566
Human Services \| Operating segments
Revenue	128,203	132,741	111,411	115,744	114,351	114,646	115,417	108,008	488,099	452,422	472,456
Gross profit	34,448	39,205	32,458	33,852	29,317	33,071	35,804	29,410	139,963	127,602	140,003
Selling, general and administrative expenses	$ (13,353)	$ (16,803)	$ (13,935)	$ (16,153)	$ (9,945)	$ (13,601)	$ (17,276)	$ (12,336)	(79,719)	(74,444)	(78,970)
Operating income									$ 60,244	$ 53,158	$ 61,033

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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