Acquisitions - Company's Pro Forma Results (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Document Period End Date			Mar. 31, 2014
Basic net income per common share attributable to controlling interest:
Diluted (in dollars per share)	$ (0.63)	$ (0.33)	$ (0.91)	$ 0.06
Basic (in dollars per share)	$ (0.63)	$ (0.33)	$ (0.91)	$ 0.08
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ (0.34)		$ 0.12
Revenues	$ 1,341.2	$ 1,411.1	$ 2,851.2	$ 2,633.4
Business Acquisition, Pro Forma Revenue		1,428.2		2,878.9
Business Acquisition, Pro Forma Net Income (Loss)		(51.4)		22.0
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ (0.34)		$ 0.08
As Initially Reported [Member]
Basic net income per common share attributable to controlling interest:
Business Acquisition, Pro Forma Net Income (Loss)		(50.5)		17.6
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		$ (0.01)		$ 0.00
Business Acquisition, Pro Forma Revenue		17.1		53.7
Business Acquisition, Pro Forma Net Income (Loss)		$ (0.9)		$ (0.5)
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ (0.01)		$ 0.00