Selected Financial Information Regarding Results of Operations of Charter Fleet Business (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposal of discontinued operations		$ 257
Total income from discontinued operations, net of tax		3,497
Charter Fleet Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues		8,184
Gain on disposal of discontinued operations	300	257
Income before provision for income taxes		3,240
Total income from discontinued operations, net of tax		$ 3,497

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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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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- Definition

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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