Reportable Segments (Details) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2016 USD ($) segment	Mar. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)
Summarized financial information concerning the Company's reportable segments
Number of reportable segments \| segment			3
Revenue	$ 4,381,296	$ 4,506,197	$ 8,678,947	$ 8,716,665
Gross profit	183,444	103,312	324,302	238,042
Equity in (loss) earnings of joint ventures	39,016	24,628	64,279	48,552
General and administrative expenses	(29,455)	(29,797)	(58,094)	(64,135)
Acquisition and integration expenses	(50,711)	(91,599)	(91,749)	(230,062)
Loss on disposal activities	(1,536)		(42,589)
Operating income (loss)	140,758	$ 6,544	196,149	$ (7,603)
Segment assets	$ 13,989,215		$ 13,989,215		$ 14,014,298
Gross profit as a % of revenue	4.20%	2.30%	3.70%	2.70%
Corporate
Summarized financial information concerning the Company's reportable segments
General and administrative expenses	$ (29,500)	$ (29,800)	$ (58,200)	$ (64,100)
Acquisition and integration expenses	(50,700)	(91,600)	(91,700)	(230,100)
Operating income (loss)	(80,200)	(121,400)	(149,900)	(294,200)
Segment assets	774,600		774,600		609,800
Design and Consulting Services
Summarized financial information concerning the Company's reportable segments
Revenue	1,966,200	2,035,900	3,828,200	3,927,600
Gross profit	97,200	53,000	176,500	99,400
Equity in (loss) earnings of joint ventures	2,200	(1,400)	5,200
Operating income (loss)	99,400	$ 51,600	181,700	$ 99,400
Segment assets	$ 7,005,100		$ 7,005,100		7,118,200
Gross profit as a % of revenue	4.90%	2.60%	4.60%	2.50%
Construction Services
Summarized financial information concerning the Company's reportable segments
Revenue	$ 1,546,200	$ 1,641,100	$ 3,258,000	$ 3,175,200
Gross profit	5,800	2,500	18,700	37,800
Equity in (loss) earnings of joint ventures	2,800	4,700	5,400	10,600
Loss on disposal activities	(1,600)		(42,600)
Operating income (loss)	7,000	$ 7,200	(18,500)	$ 48,400
Segment assets	$ 3,444,000		$ 3,444,000		3,382,400
Gross profit as a % of revenue	0.40%	0.20%	0.60%	1.20%
Management Services
Summarized financial information concerning the Company's reportable segments
Revenue	$ 868,800	$ 829,200	$ 1,592,700	$ 1,613,900
Gross profit	80,400	47,700	129,100	100,800
Equity in (loss) earnings of joint ventures	34,100	21,400	53,700	38,000
Operating income (loss)	114,500	$ 69,100	182,800	$ 138,800
Segment assets	$ 2,765,500		$ 2,765,500		$ 2,903,900
Gross profit as a % of revenue	9.30%	5.80%	8.10%	6.20%

The percentage of gross profit to total net revenue from services rendered.

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