EARNINGS PER SHARE (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share Reconciliation [Abstract]
Basic									48,019	46,991	46,743
Dilutive effect of stock options and deferred stock compensation									1,056	921	669
Diluted									49,075	47,912	47,412
Earnings from continuing operations	$ 0.96	$ 0.92	$ 0.90	$ 0.76	$ 0.95	$ 0.81	$ 0.73	$ 0.48	$ 3.54	$ 2.97	$ 2.23
Earnings from continuing operations	$ 0.94	$ 0.90	$ 0.87	$ 0.74	$ 0.92	$ 0.79	$ 0.72	$ 0.48	$ 3.46	$ 2.91	$ 2.20
Earnings from continuing operations	$ 46,132	$ 44,378	$ 43,009	$ 36,430	$ 44,700	$ 38,079	$ 34,035	$ 22,590	$ 169,949	$ 139,404	$ 104,081

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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 share based payment arrangements using the treasury stock 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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