Earnings Per Share - Computation of Basic and Diluted Earnings Per Share for Continuing Operations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Numerator:
Income from continuing operations after income tax expense	$ 21,798	$ 19,503
Basic
Weighted average common shares outstanding	51,572	48,146
Diluted
Stock options	831	778
Restricted stock awards	337	358
Contingent shares	5	95
Convertible senior subordinated notes		2,008
Diluted weighted average common shares outstanding	52,745	51,385
Basic earnings per share from continuing operations	$ 0.42	$ 0.41
Diluted earnings per share from continuing operations	$ 0.41	$ 0.38

Incremental common shares attributable to restricted stock awards.

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Incremental common shares attributable to stock options.

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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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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of contingently issuable shares. Contingently issuable shares are those shares that are issuable for little or no cash contingent on certain conditions being met.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible debt securities using the if-converted method.

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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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