Pending Merger Transaction - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
Oct. 08, 2014	Dec. 31, 2014	Oct. 08, 2014	Sep. 30, 2014
Business Acquisition [Line Items]
Common stock, par value	$ 0.33	$ 0.33	$ 0.33	$ 0.33
Reverse stock split	0.3333
Common stock, shares outstanding	7,333,708us-gaap_CommonStockSharesOutstanding	8,077,580us-gaap_CommonStockSharesOutstanding	7,333,708us-gaap_CommonStockSharesOutstanding	8,065,233us-gaap_CommonStockSharesOutstanding
Split-effected Common Stock	1.760
Amount payable in the event of Merger Agreement termination	$ 2.0		$ 2.0
Company or TGC \| Maximum
Business Acquisition [Line Items]
Amount payable in the event of Merger Agreement termination	$ 1.5		$ 1.5
Before Reverse Stock Split
Business Acquisition [Line Items]
Common stock, par value	$ 0.01		$ 0.01
Common stock, shares outstanding	22,001,125		22,001,125

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For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

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Face amount or stated value per share of common stock.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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The number of shares converted in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

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