Discontinued Operations - Consolidated Statement of Comprehensive Income (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	$ 10,927,150	$ 13,130,554	$ 12,422,318
Cost of sales	(6,696,602)	(7,855,827)	(7,279,787)
Distribution, general & administrative	(1,559,021)	(2,643,821)	(2,666,911)
Maintenance	(175,509)	(239,321)	(263,559)
Depreciation & amortization	(541,777)	(925,389)	(989,535)
Taxes other than income	(326,214)	(395,145)	(363,802)
Other income (expense)	23,597	5,098	89,048
Interest expense	(1,603)	(25,268)	(23,615)
Pretax income from discontinued operations	1,650,021	1,050,881	924,157
Loss on sale of discountinued operations	0	(7,915)	0
Total pretax income from discontinued operations	1,650,021	1,042,966	924,157
Income tax expense	(617,410)	(223,828)	(400,328)
Income from discontinued operations	$ 1,032,611	$ 819,138	$ 523,829

Amount of maintenance expense attributable to disposal group.

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Amount of operating other income or expenses recognized or incurred in disposal of discontinued operations during the reporting period.

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Amount of tax expense attributable to disposal group.

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Amount of gain (loss), after tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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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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Pretax income (loss) from operations of a business component (exclusive of any gain (loss) on disposal, or provision therefore) during the reporting period, until its 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 costs of goods sold attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Amount of depreciation and amortization attributable to disposal group.

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Amount of general and administrative expense attributable to disposal group.

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Amount of interest expense allocated to disposal group, including a discontinued operation.

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Amount of sales or other form of revenues attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Amount of income (loss) from a disposal group, net of income tax before extraordinary items 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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