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Derivatives - Summary of Fair Value of Open Commodity Derivatives (Detail) (Commodity derivatives [Member], Derivative not designated as hedging instruments, fair value of assets derivative [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Commodity derivatives [Member] | Derivative not designated as hedging instruments, fair value of assets derivative [Member]
Derivatives, Fair Value [Line Items]
Unrealized (loss) gain on commodity derivatives	$ (1,666)	$ 2,433

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- Definition

Derivative Instruments Not Designated As Hedging Instruments Asset Liability At Fair Value

+ References

No definition available.

+ Details

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Namespace Prefix:	arex_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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- Details

Name:	us-gaap_DerivativesFairValueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration