EQUITY (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 19, 2016
Stock-based compensation
Number of shares reserved to be granted under the plan	2,000,000
Number of shares available for grant	723,000
Treasury Stock
Shares Repurchased	45,807	171,907	171,907
Aggregate Cost	$ 2,582,000	$ 12,437,000	$ 12,983,000
Shares repurchased to satisfy tax withholdings and exercise obligations	42,703	141,180	32,814
Aggregate cost to satisfy tax withholdings and exercise obligations	$ 2,419,000	$ 10,859,000	$ 2,348,000
Average Repurchase Price (in dollars per share)	$ 56.65	$ 76.76	$ 72.50
Number of Options
Exercised (in shares)	(17,000)	(158,021)	(158,021)
Stock-based compensation, additional disclosures
Cash proceeds received upon exercise of options		$ 72,000	$ 1,030,000
2016 Repurchase Plan
Treasury Stock
Authorized amount				$ 50,000,000.0
Shares Repurchased	3,104	30,427	201,932
Aggregate Cost	$ 162,000	$ 1,577,000	$ 10,636,000
Average Repurchase Price (in dollars per share)	$ 52.37	$ 51.82	$ 52.67
Value of shares available for repurchase	$ 37,500,000
Stock options
Stock-based compensation
Expiration term	10 years
Vesting period	4 years
Number of Options
Outstanding at the beginning of the period (in shares)	42,000	200,021
Granted (in shares)	0	0
Forfeited (in shares)	(7,500)
Expired (in shares)	(2,500)
Exercised (in shares)	(17,000)	(158,021)
Outstanding at the end of the period (in shares)	15,000	42,000	200,021
Vested and expected to vest at the end of the period (in shares)	15,000	42,000
Exercisable at the end of the period (in shares)	15,000	33,250
Weighted Avg. Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 48.61	$ 41.76
Forfeited (in dollars per share)	52.97
Expired (in dollars per share)	52.97
Exercised (in dollars per share)	45.39	39.95
Outstanding at the end of the period (in dollars per share)	49.34	48.61	$ 41.76
Vested and expected to vest at the end of the period (in dollars per share)	49.34	48.61
Exercisable at the end of the period (in dollars per share)	$ 49.34	$ 46.76
Weighted Average Remaining Contractual Term
Outstanding	3 years 2 months 12 days	4 years 1 month 6 days
Vested and expected to vest	3 years 2 months 12 days	4 years 1 month 6 days
Exercisable	3 years 2 months 12 days	3 years
Aggregate Intrinsic Value
Outstanding	$ 170,900	$ 823,515
Vested and expected to vest	170,900	962,840
Exercisable	170,900	823,515
Stock-based compensation, additional disclosures
Weighted-average fair value of options granted (in dollars per share)			$ 13.77
Aggregate intrinsic value of options exercised	229,000	5,927,000	$ 936,000
Cash proceeds received upon exercise of options		72,000	$ 1,030,000
Weighted-average assumptions using Black-Scholes option-pricing model for estimating fair value of each option granted
Risk-free interest rate (as a percent)			1.79%
Expected dividend yield (as a percent)			1.28%
Expected life			4 years
Expected volatility (as a percent)			34.01%
Stock compensation expense
Stock compensation expense	$ 0	100,000	$ 100,000
Restricted Stock
Stock-based compensation
Vesting period	4 years
Unamortized stock based compensation
Unamortized stock based compensation	$ 8,200,000
Weighted-average period for recognition of unamortized stock-based compensation cost	2 years 4 months 24 days
Stock compensation expense
Stock compensation expense	$ 6,400,000	$ 6,100,000	$ 6,600,000
Shares
Unvested at the beginning of the period (in shares)	200,653	214,938
Granted (in shares)	108,278	111,474	95,095
Forfeited (in shares)	(18,579)	(31,327)
Vested and issued (in shares)	(86,206)	(94,432)
Unvested at the end of the period (in shares)	204,146	200,653	214,938
Weighted Avg. Fair Value
Unvested at the beginning of the period (in dollars per share)	$ 65.21	$ 68.62
Granted (in dollars per share)	54.68	59.52
Forfeited (in dollars per share)	57.04	66.53
Vested and issued (in dollars per share)	65.77	66.27
Unvested at the end of the period (in dollars per share)	$ 60.13	$ 65.21	$ 68.62
Restricted Stock | Management
Stock compensation expense
Stock compensation expense		$ 200,000	$ 300,000