Acquisitions - Company's Pro Forma Results (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Document Period End Date	Dec. 31, 2013
Basic net income per common share attributable to controlling interest:
Diluted (in dollars per share)	$ (0.28)	$ 0.03
Basic (in dollars per share)	$ (0.28)	$ 0.31
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 0.35
Revenues	$ 1,510.0	$ 1,222.3
Business Acquisition, Pro Forma Revenue		1,450.6
Business Acquisition, Pro Forma Net Income (Loss)		73.6
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 0.05
As Initially Reported [Member]
Basic net income per common share attributable to controlling interest:
Business Acquisition, Pro Forma Net Income (Loss)		68.1
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)		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		36.5
Business Acquisition, Pro Forma Net Income (Loss)		$ 0.6
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 0.00