STOCK BASED PLANS (Summary of Restricted Stock Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Weighted Average Grant Date Fair Value
Stock based compensation expense	$ 3,069	$ 2,684
Restricted Stock
Restricted stock activity
Restricted stock outstanding at the beginning of the period (in shares)	406,544
Granted (in shares)	150,216
Forfeited (in shares)	(1,981)
Restricted stock outstanding at the end of the period (in shares)	554,779
Weighted Average Grant Date Fair Value
Restricted stock outstanding at the beginning of the period (in dollars per share)	$ 82.10
Granted (in dollars per share)	84.48
Forfeited (in dollars per share)	70.94
Restricted stock outstanding at the end of the period (in dollars per share)	$ 82.78
Stock based compensation expense	$ 2,300	2,000
Share based compensation costs capitalized	$ 300	$ 300

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Represents the compensation cost capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, units, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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