Discontinued Operations - Summary of Discontinued Operations based on Results of Operations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Costs and expenses:
Exploratory expenses		$ 204	$ 2,545
Depreciation, depletion and amortization		8	53
General and administrative expenses	36	779	1,642
Other income			(228)
Total costs and expenses	36	991	4,012
Loss before income taxes	(36)	(991)	(4,012)
Income tax expense	0	0	0
Net loss before noncontrolling interests	(36)	(991)	(4,012)
Noncontrolling interests		8	90
Net loss	$ (36)	$ (983)	$ (3,922)

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Amount of expense from discontinued operations, that reflects the allocation of the cost of tangible and intangible assets over the assets' useful lives.

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Other income (loss) amounts, net of tax expense or benefit, relating to a disposal group that is classified as a component of the entity, exclusive of the following elsewhere enumerated categories: income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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Overall income (loss) from a disposal group that is classified as a component of the entity, before income tax, reported as a separate component of income before extraordinary items. Includes the following (before income tax): income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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Tax effect allocated to a disposal group that is classified as a component of the entity reported as a separate component of income before extraordinary items. Includes the tax effects of the following: income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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Amount of general and administrative expense attributable to disposal group.

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Amount of operating expenses attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Amount of other expense attributable to disposal group.

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Amount of other income attributable to disposal group.

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This element represents the overall income (loss) from a disposal group that is classified as a component of the entity, net of income tax, reported as a separate component of income before extraordinary items, which is apportioned to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This item includes the following (net of tax): income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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Amount of income (loss) from a disposal group, net of income tax, reported as a separate component of income before extraordinary items after deduction or consideration of the amount allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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