Acquisition - Acquisition Acquired Activities (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Revenue, Consolidated As Reported	$ 168,839	$ 149,841	$ 542,784	$ 491,603
Revenue, Pro Forma Adjustments		10,694		35,487
Revenue, Pro Forma Consolidated		160,535		527,090
Income from continuing operations after income tax expense, Consolidated As Reported	5,081	3,082	27,435	24,029
Income from continuing operations after income tax expense, Pro Forma Adjustments		653		2,734
Income from continuing operations after income tax expense, Pro Forma Consolidated		$ 3,735		$ 26,763
Earnings per share from continuing operations:
Basic, Consolidated As Reported	$ 0.10	$ 0.06	$ 0.56	$ 0.49
Basic, Pro Forma Adjustments		$ 0.01		$ 0.05
Basic, Pro Forma Consolidated		$ 0.07		$ 0.54
Diluted, Consolidated As Reported	$ 0.10	$ 0.06	$ 0.55	$ 0.49
Dilutes, Pro Forma Adjustments		$ 0.01		$ 0.05
Diluted, Pro Forma Consolidated		$ 0.07		$ 0.54
Weighted average common shares outstanding:
Basic, Weighted average common shares outstanding	48,504	48,895	49,187	49,014
Basic, Weighted average common shares outstanding pro forma Adjustments		456		564
Basic, Weighted average common shares outstanding pro forma Consolidated		49,351		49,578
Diluted, Weighted average common shares outstanding	49,003	49,109	49,537	49,278
Diluted, Weighted average common shares outstanding pro forma Adjustments		456		565
Diluted, Weighted average common shares outstanding pro forma Consolidated		49,565		49,843

Business acquisitions pro forma income loss from continuing operations net of tax adjustments.

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Business acquisitions pro forma revenue adjustments.

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Income loss from continuing operations net of tax per share basic adjustment pro forma.

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Income loss from continuing operations net of tax per share diluted adjustment pro forma.

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The pro forma income from continuing operations before changes in accounting and extraordinary items, net of tax effect per basic share of common stock for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma income from continuing operations before changes in accounting and extraordinary items, net of tax effect, per diluted share of common stock for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma income from continuing operations before changes in accounting and extraordinary items, net of tax effect, for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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Amount of income (loss) from continuing operations attributable to the parent. Also defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests.

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The amount of net income (loss) from continuing operations per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) derived from continuing operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The weighted average number of shares or units and dilutive common stock or unit equivalents outstanding in the calculation of proforma diluted earnings per share (earnings per unit), which is commonly presented in initial public offerings based on the terms of the offering.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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The weighted average number of shares (units) outstanding in the calculation of pro forma basic earnings per share (earnings per unit), which is commonly presented in initial public offerings based on the terms of the offering.

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Adjustment to the weighted average number of basic shares outstanding to convert this to a pro forma presentation.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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