Discontinued Operations - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
Dec. 31, 2012	Dec. 31, 2012
Discontinued Operations [Line Items]
Cash sale of Quanta's telecommunication subsidiaries		$ 265,000,000
Pre tax gain in discontinued operations		17,962,000
Incremental expense related to accelerated vesting	3,700,000	3,700,000
Telecommunications [Member]
Discontinued Operations [Line Items]
Cash sale of Quanta's telecommunication subsidiaries		265,000,000
Pre tax gain in discontinued operations		17,962,000
Tax amount from gain loss of disposal of discontinued operations		(32,200,000)
Loss on sale, Net of tax		$ (14,200,000)

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

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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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Tax benefit from provision recognizing a loss for initial, or subsequent, write-down to fair value (less cost to sell) of a of a disposal group that is classified as a component of the entity, which remains unsold as of the reporting date. May include a tax on the (gain) for the recognition of a subsequent increase in fair value (less cost to sell), but not in excess of the cumulative loss previously recognized through write-downs.

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This element represents the cash inflow during the period from the sale of a component of the entity.

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