Acquisitions - Additional Information (Detail) - Entity [Domain] - USD ($) $ in Millions					3 Months Ended		6 Months Ended	9 Months Ended
		Nov. 03, 2014	Oct. 31, 2014	Oct. 01, 2014	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015	Jun. 30, 2015	Jun. 30, 2014	May. 21, 2015	Dec. 31, 2014	Oct. 06, 2014	Sep. 30, 2014
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Net Income (Loss)					$ (37.0)	$ 146.4		$ (392.7)	$ 81.1
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent								35.00%
Goodwill					2,498.7			$ 2,498.7					$ 1,524.8
Minimum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life								2 years
Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life								20 years
Trade Names [Member] | Minimum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life								3 years
Trade Names [Member] | Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life								13 years
Technology assets [Member] | Minimum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life								4 years
Technology assets [Member] | Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life								17 years
Customer Relationships [Member]
Business Acquisition [Line Items]
Retention Rate										95.00%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent								38.00%
Business Acquisition Contingent Consideration Key Assumptions Discount Rate								9.50%
Customer Relationships [Member] | Minimum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life								2 years
Customer Relationships [Member] | Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life								20 years
AAG Acquisition [Member]
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Net Income (Loss)	[1]				4.4	$ 4.9		$ (7.4)	$ (3.0)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net										$ 931.4
Business Combination, Consideration Transferred					931.4
Goodwill										965.7
Payments to Acquire Businesses, Gross					$ 1,400.0
AAG Acquisition [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles										$ 0.0
Finite-Lived Intangible Asset, Useful Life								15 years
AAG Acquisition [Member] | Customer Relationships [Member] | Minimum [Member]
Business Acquisition [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate								2.00%
AAG Acquisition [Member] | Customer Relationships [Member] | Maximum [Member]
Business Acquisition [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate								12.10%
Compass Production Partners [Member]
Business Acquisition [Line Items]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain			$ 141.2
Proved Developed and Undeveloped Oil and Natural Gas Properties, Period Increase (Decrease)			145.4
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets, Current			$ 56.1
Business Acquisition Percentage Of Equity Interests Acquired			99.80%									25.50%
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Unproved Oil and Natural Gas Properties			$ 26.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Proved Developed and Undeveloped Oil and Natural Gas Properties			767.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable			23.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other			1.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Asset Retirement Obligations			$ 36.0
Ability Re [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 19.2
Payments to Acquire Businesses, Gross		$ 17.9
General Partner [Member]
Business Acquisition [Line Items]
Business Acquisition Percentage Of Equity Interests Acquired			100.00%
Tell Manufacturing [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net				$ 30.3
Goodwill				7.1							$ 115.7
Tell Manufacturing [Member] | Trade Names [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				$ 4.0
Tell Manufacturing [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Retention Rate				90.00%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				38.00%
Business Acquisition Contingent Consideration Key Assumptions Discount Rate							20.00%
Acquired Finite-lived Intangible Asset, Residual Value				$ 8.5
Finite-Lived Intangible Asset, Useful Life				13 years
Tell Manufacturing [Member] | Customer Relationships [Member] | Minimum [Member]
Business Acquisition [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate				2.50%
Tell Manufacturing [Member] | Customer Relationships [Member] | Maximum [Member]
Business Acquisition [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate				7.10%
Cost Approach Valuation Technique [Member] | Tell Manufacturing [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment, Measurement Basis, Percentage of Total				97.00%
Market Approach Valuation Technique [Member] | Tell Manufacturing [Member]
Business Acquisition [Line Items]
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment, Measurement Basis, Percentage of Total				3.00%
Impairment, Trade Names [Member] | AAG Acquisition [Member]
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Net Income (Loss)								$ 7.0

[1] (a) The AAG adjustment for the three and nine months ended June 30, 2015 excludes non-recurring debt extinguishment expense of $35.7 related to the retirement of AAG debt in relation with the AAG Acquisition and acquisition related costs incurred by AAG prior to May 21, 2015 of $25.2. The AAG adjustment for the nine months ended June 30, 2015 also excludes a non-recurring tradename impairment of $7.0