Acquisitions - Company's Pro Forma Results (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Document Period End Date			Jun. 30, 2014
Basic net income per common share attributable to controlling interest:
Diluted (in dollars per share)	$ 0.28	$ 0.25	$ (0.52)	$ 0.30
Basic (in dollars per share)	$ 0.28	$ 0.45	$ (0.52)	$ 0.54
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 0.45		$ 0.58
Revenues	$ 1,599.4	$ 1,409.2	$ 4,450.6	$ 4,042.6
Business Acquisition, Pro Forma Revenue		1,409.2		4,288.1
Business Acquisition, Pro Forma Net Income (Loss)		118.7		140.7
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 0.25		$ 0.32
As Initially Reported [Member]
Basic net income per common share attributable to controlling interest:
Business Acquisition, Pro Forma Net Income (Loss)		118.7		136.3
HHI Business [Member] | Adjustments [Member]
Basic net income per common share attributable to controlling interest:
Business Acquisition, Pro Forma Earnings Per Share, Basic				$ 0.04
Business Acquisition, Pro Forma Revenue				191.8
Business Acquisition, Pro Forma Net Income (Loss)		0		4.9
Business Acquisition, Pro Forma Earnings Per Share, Diluted				$ 0.02
EXCO/HGI JV [Member] | Adjustments [Member]
Basic net income per common share attributable to controlling interest:
Business Acquisition, Pro Forma Earnings Per Share, Basic				$ 0.00
Business Acquisition, Pro Forma Revenue		0		53.7
Business Acquisition, Pro Forma Net Income (Loss)				$ (0.5)
Business Acquisition, Pro Forma Earnings Per Share, Diluted				$ 0.00