Acquisitions - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended				12 Months Ended				12 Months Ended						9 Months Ended		0 Months Ended		0 Months Ended																	0 Months Ended											0 Months Ended		0 Months Ended
	Apr. 06, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Apr. 08, 2011	Sep. 30, 2013 HGI	Sep. 30, 2012 HGI	Sep. 30, 2011 HGI	Feb. 14, 2013 EXCO/HGI JV	Sep. 30, 2013 Minimum	Sep. 30, 2013 Maximum	Sep. 30, 2013 Technology assets Minimum	Sep. 30, 2013 Technology assets Maximum	Sep. 30, 2013 Customer relationships Minimum	Sep. 30, 2013 Customer relationships Maximum	Sep. 30, 2013 Hardware Acquisition Business Combination Measurement Period Adjustment	Dec. 17, 2012 Hardware Acquisition Business Combination Measurement Period Adjustment	Dec. 17, 2012 HHI Business	Sep. 30, 2013 HHI Business	Dec. 17, 2012 HHI Business Technology assets	Dec. 17, 2012 HHI Business Technology assets Minimum	Dec. 17, 2012 HHI Business Technology assets Maximum	Dec. 17, 2012 HHI Business Trade name license agreement	Dec. 17, 2012 HHI Business Trade name license agreement Minimum	Dec. 17, 2012 HHI Business Trade name license agreement Maximum	Dec. 17, 2012 HHI Business Trade Name	Dec. 17, 2012 HHI Business Trade Name Minimum	Dec. 17, 2012 HHI Business Trade Name Maximum	Dec. 17, 2012 HHI Business Customer relationships	Dec. 17, 2012 HHI Business Customer relationships Minimum	Dec. 17, 2012 HHI Business Customer relationships Maximum	Dec. 17, 2012 HHI Business Trademarks and trade names	Dec. 17, 2012 HHI Business Trademarks and trade names Minimum	Dec. 17, 2012 HHI Business Trademarks and trade names Maximum	Sep. 30, 2013 Shaser Biosciences, Inc.	Nov. 08, 2012 Shaser Biosciences, Inc.	Nov. 08, 2012 Shaser Biosciences, Inc. Noncontrolling Interest	Nov. 08, 2012 Shaser Biosciences, Inc. Technology assets	Nov. 08, 2012 Shaser Biosciences, Inc. Call Option exercisable between January 1, 2017 and March 31, 2017	Sep. 30, 2013 Shaser Biosciences, Inc. Business Combination Measurement Period Adjustment	Feb. 14, 2013 EXCO/HGI JV EXCO	Feb. 14, 2013 EXCO/HGI JV HGI	Feb. 14, 2013 EXCO/HGI JV	Feb. 14, 2013 EXCO/HGI JV HGI Energy Holdings, LLC	Feb. 14, 2013 EXCO/HGI JV EXCO/HGI General Partner	Mar. 05, 2013 Cotton-Valley Oil and Gas Properties HGI	Mar. 05, 2013 Cotton-Valley Oil and Gas Properties EXCO/HGI JV	Apr. 06, 2011 FGL	Sep. 30, 2013 FGL	Oct. 31, 2011 BlackFlag	Dec. 22, 2011 FURminator	Dec. 03, 2010 Seed Resources L L C [Member]	Sep. 30, 2012 Seed Resources L L C [Member]	Sep. 30, 2011 Surplus Note FGL
Business Acquisition [Line Items]
Goodwill (Note 13)		$ 1,476,700,000	$ 694,200,000	$ 610,300,000													$ 10,100,000	$ 662,100,000	$ 717,800,000																$ 67,200,000	$ 63,900,000				$ 3,300,000										$ 15,900,000	$ 68,500,000		$ 10,000,000
Deferred tax liability - long-term																	9,800,000	104,700,000	116,400,000
Property, plant and equipment																	(2,900,000)	104,500,000	138,400,000																															400,000	700,000
Goodwill, Purchase Accounting Adjustments																7,700,000
Inventory adjustment to fair value																		31,000,000
Property, plant and equipment, net adjustment to fair value																		10,000,000
Intangible asset																2,000,000	2,000,000	470,000,000	489,100,000																29,300,000	35,500,000				(6,200,000)
Estimated sales growth rate																					2.50%	31.00%		2.50%	5.00%		2.50%	15.50%		2.50%	15.50%		2.50%	5.00%			3.00%	3.00%
Customer retention rate																													95.00%
Estimated Income tax rate		35.00%																		35.00%			35.00%				17.00%	35.00%		17.00%	35.00%	35.00%					35.00%	35.00%
Discounted rate																				12.00%			12.00%			12.00%			12.00%			12.00%					17.00%	11.00%
Carrying value, intangible asset																				51,000,000			13,000,000			4,100,000			90,000,000			331,000,000						29,300,000
Amortization period, intangible asset										1 year	20 years	4 years	17 years	15 years	20 years								5 years			8 years			20 years									13 years
Royalty rate																					4.00%	5.00%	4.00%				1.00%	3.50%					3.00%	5.00%				10.50%
Expected terminal year growth rate																																2.50%
Remaining legal life																				10 years
Deferred tax liabilities, net																		123,600,000
Business Acquisition Percentage Of Equity Interests Acquired																																				56.00%			44.00%		24.50%	74.50%		73.50%	2.00%
Business Combination Purchase Consideration Transferred																																									725,000,000	349,800,000	574,800,000
Non-controlling interest																	1,700,000	2,200,000	3,900,000																39,100,000	39,000,000	39,000,000			100,000	119,100,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Change in Working Capital and Other Assets (Net)																7,000,000
Preliminary working capital and other adjustments																		(10,700,000)																		(400,000)						30,500,000
Business Acquisition, Contingent Consideration, at Fair Value, Noncurrent (Deprecated 2013-01-31)																																																				2,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill																																																		25,000,000	79,000,000		1,100,000
Insurance Assets Transferred At Fair Value Net					653,700,000
Long-term Debt, Gross																																																						95,000,000
Reserve Credit Facility Structuring Fee				13,800,000
Inventory																	100,000	207,200,000	208,400,000																															2,500,000
Trailing revenues																																							100.00%
Adjusted trailing EBITDA																																							700.00%
Purchase price																	(16,100,000)	629,400,000	661,200,000																21,600,000	24,700,000				(3,100,000)		694,500,000	517,600,000			130,700,000	97,400,000
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Oil And Natural Gas Properties																																										697,300,000	519,500,000			138,100,000	102,900,000
Other long-term liabilities																	400,000	11,200,000	19,700,000																							24,800,000	18,500,000			7,400,000	5,500,000
Cash consideration		2,014,800,000	185,100,000	(684,400,000)																																												350,000,000
Reduction in purchase price																																																50,000,000
Cash consideration re-characterized as expense																																																5,000,000
Acquisition related charges	22,700,000					12,700,000	3,700,000	8,700,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Gas Gathering Assets									21,500,000
Insurance obligations under annuity contract																																																3,000,000,000
Maximum amount of asset securing reinsurance obligations																																																1,000,000,000
Maximum amount required to pay under Front Street Reinsurance Transaction																																																50,000,000
Fair value assigned to the contingent purchase price reduction																																																0
Business Combination, Contingent Consideration, Asset																																																	41,000,000
Amount Of Settlement Adjustments Under Commitment Agreement			11,200,000
Maximum Period Of Measurement Period		1 year
Business Combination, Consideration Transferred																																																		43,800,000	141,800,000	12,500,000
Business Acquisition, Purchase Price Allocation, Current Assets (Deprecated 2013-01-31)																																																			9,200,000
Business Acquisition, Purchase Price Allocation, Liabilities Assumed (Deprecated 2013-01-31)																																																			15,700,000
Payments to Acquire Businesses, Gross																																																				$ 10,500,000