Acquisitions - Summary of Amounts Recorded in Connection with Acquisition of Business (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended			12 Months Ended															0 Months Ended	3 Months Ended					0 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2014 The Liquid Fence Company [Member]	Jan. 02, 2014 The Liquid Fence Company [Member]	May 30, 2014 FOHG [Member]	Feb. 14, 2013 EXCO/HGI General Partner EXCO	Feb. 14, 2013 Compass EXCO	Feb. 14, 2013 Compass HGI	Feb. 14, 2013 Compass	Mar. 05, 2013 Cotton-Valley Oil and Gas Properties HGI	Mar. 05, 2013 Cotton-Valley Oil and Gas Properties Compass	Sep. 30, 2014 HHI Business	Sep. 30, 2013 HHI Business	Dec. 17, 2012 HHI Business	Apr. 08, 2013 TLM Taiwan	Sep. 30, 2014 Hardware Acquisition Business Combination Measurement Period Adjustment	Apr. 08, 2013 Hardware Acquisition Business Combination Measurement Period Adjustment	Nov. 08, 2013 Shaser Biosciences, Inc.	Dec. 31, 2013 Shaser Biosciences, Inc.	Sep. 30, 2013 Shaser Biosciences, Inc.	Nov. 08, 2012 Shaser Biosciences, Inc.	Sep. 30, 2013 Shaser Biosciences, Inc. Business Combination Measurement Period Adjustment	Jan. 02, 2014 Customer relationships The Liquid Fence Company [Member]	Dec. 07, 2012 Minimum Trade Name HHI Business	Dec. 07, 2012 Minimum Customer relationships HHI Business
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents					$ 0	$ 0.8
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value	12.0
Payments to Acquire Businesses, Gross	1.5			24.8															50.0
Estimated Income tax rate	35.00%																								17.00%	17.00%
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Cash									0.1	0.1	0	0		24.0	17.4	0.8		5.8			0.9	0.9	0
Accounts receivable														108.6	104.6	0		4.0
Inventory					2.2	12.4								208.4	207.2	1.1		0.1
Prepaid expenses and other														9.3	13.3	2.2		(6.2)
Property, plant and equipment						1.2								138.4	104.5	36.8		(2.9)
Intangible asset													489.1	489.1	470.0	17.1	2.0	2.0			29.3	35.5	(6.2)	1.3
Other long-term assets									32.7	24.5	0	0		7.6	3.1	0.1		4.4			0.2	2.7	(2.5)
Total assets acquired														985.4	920.1	58.1		7.2			30.4	39.1	(8.7)
Accounts payable														138.1	130.1	0		8.0
Deferred tax liability - current														7.2	7.1	0		0.1
Accrued liabilities									(10.8)	8.0	0	0		(42.8)	(37.6)	(0.2)		(5.0)
Deferred tax liability - long-term						0								116.4	104.7	1.9		9.8
Other long-term liabilities									(24.8)	(18.5)	(7.4)	(5.5)		19.7	11.2	8.1		0.4
Total liabilities assumed														324.2	290.7	10.2		23.3			8.8	14.4	(5.6)
Total identifiable net assets									694.5	517.6	130.7	97.4		661.2	629.4	47.9		(16.1)			21.6	24.7	(3.1)
Non-controlling interests						(8.3)		(119.1)						(3.9)	(2.2)	0		(1.7)			(39.1)	(39.0)	(0.1)
Goodwill (Note 13)	1,524.8	1,476.7	694.2		7.0	43.9								717.8	662.1	45.6		10.1			67.2	63.9	3.3
Total net assets acquired					35.8	13.5								1,375.1	1,289.3	93.5		(7.7)			49.7	49.6	0.1
Oil and natural gas properties
Unproved oil and natural gas properties									65.1	48.5	7.2	5.4
Proved developed and undeveloped oil and natural gas properties									632.2	471.0	130.9	97.5
Total oil and natural gas properties									697.3	519.5	138.1	102.9
Business Acquisition Percentage Of Equity Interests Acquired							50.00%	24.50%	74.40%
Preliminary working capital and other adjustments									30.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill					26.9	41.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets					30.4	59.6
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities					1.6	81.7
Business Combination Purchase Consideration Transferred								(725.0)	(349.8)	(574.8)
Business Combination, Consideration Transferred, Liabilities Incurred				9.5
Business Combination, Consideration Transferred, Other				1.5															(0.4)	0.1
Business Combination, Consideration Transferred				35.8															49.7
Business Combination, Consideration Transferred, Including Equity Interest in Acquiree Held Prior to Combination	13.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables					1.2	0.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets					0.1	2.8
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net					$ 28.8	$ (22.1)