STOCK-BASED PLANS (Summary of Stock Option Activity) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Nov. 09, 2010
Stock-based plans
Shares of common stock reserved for issuance (in shares)				3,698,050
Stock based compensation expense	$ 19,502,000	$ 12,128,000	$ 7,385,000
Stock Options
Stock options outstanding at the beginning of the period (in shares)	817,998	783,182	1,176,640
Granted (in shares)	21,500	265,000	58,000
Exercised (in shares)	(39,402)	(183,592)	(395,482)
Forfeited (in shares)	(65,800)	(46,592)	(54,976)
Expired (in shares)	(12,800)		(1,000)
Stock options outstanding at the end of the period (in shares)	721,496	817,998	783,182
Stock options exercisable at the end of the period (in shares)	256,296
Stock options vested and expected to vest (in shares)	705,947
Weighted Average Exercise Price
Stock options outstanding at the beginning of the period (in dollars per share)	$ 105.06	$ 90.22	$ 78.87
Granted (in dollars per share)	105.37	124.56	119.85
Exercised (in dollars per share)	63.73	65.72	58.81
Forfeited (in dollars per share)	128.02	121.34	105.17
Expired (in dollars per share)	143.45		57.77
Stock options outstanding at the end of the period (in dollars per share)	104.55	$ 105.06	$ 90.22
Stock options exercisable at the end of the period (in dollars per share)	76.61
Stock options vested and expected to vest (in dollars per share)	$ 104.17
Weighted Average Remaining Contractual Term (In Years) [Abstract]
Weighted average remaining contractual term of stock options outstanding	5 years 6 months
Weighted average remaining contractual term of stock options exercisable	2 years
Weighted average remaining contractual term of stock options expected to vest	5 years 4 months 24 days
Aggregate Intrinsic Value [Abstract]
Aggregate intrinsic value	$ 17,098,603
Aggregate intrinsic value of stock options exercisable	13,356,723
Aggregate intrinsic value of stock options expected to vest	$ 17,011,899
Maximum
Stock-based plans
Maximum number of shares available for future grant	1,697,667
Employee Stock Option [Member]
Stock-based plans
Stock based compensation expense	$ 1,800,000	$ 12,100,000	$ 8,400,000
Share based compensation costs capitalized	400,000	2,400,000	1,100,000
Stock Options
Stock-based plans
Stock based compensation expense	$ 1,400,000	$ 2,200,000	$ 1,600,000
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 104.56
Number Outstanding (in shares)	721,496
Weighted Average Remaining Contractual Term	5 years 6 months
Number Exercisable (in shares)	256,296
Significant assumptions used in Black-Scholes option-pricing model
Grant date fair value (in dollars per share)	$ 32.51	$ 48.27	$ 34.51
Weighted-average expected life of options	7 years 6 months	8 years 4 months 24 days	8 years 4 months 24 days
Weighted-average risk-free interest rate (as a percent)	2.20%	2.70%	2.20%
Weighted-average expected volatility (as a percent)	22.60%	24.70%	22.80%
Expected annual dividend per share	$ 0	$ 0	$ 0
Expiration period	10 years
Unamortized stock option expense	$ 10,600,000
Weighted-average period for recognition of unamortized stock expense	4 years 9 months 18 days
Stock Options | Minimum
Significant assumptions used in Black-Scholes option-pricing model
Exercisable period	5 years
Stock Options | $46.49 - 55.82
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 48.38
Number Outstanding (in shares)	8,775
Weighted Average Remaining Contractual Term	1 year 9 months 18 days
Number Exercisable (in shares)	8,775
Stock Options | $46.49 - 55.82 | Minimum
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 46.46
Stock Options | $46.49 - 55.82 | Maximum
Exercise price range of stock options
Exercise Price (in dollars per share)	55.82
Stock Options | $57.77 - 60.33
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 58.03
Number Outstanding (in shares)	131,874
Weighted Average Remaining Contractual Term	1 year 2 months 12 days
Number Exercisable (in shares)	131,874
Stock Options | $57.77 - 60.33 | Minimum
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 57.77
Stock Options | $57.77 - 60.33 | Maximum
Exercise price range of stock options
Exercise Price (in dollars per share)	60.33
Stock Options | $61.64 - 69.75
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 66.75
Number Outstanding (in shares)	47,529
Weighted Average Remaining Contractual Term	2 years 3 months 18 days
Number Exercisable (in shares)	47,529
Stock Options | $61.64 - 69.75 | Minimum
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 61.64
Stock Options | $61.64 - 69.75 | Maximum
Exercise price range of stock options
Exercise Price (in dollars per share)	69.75
Stock Options | $81.80 - 110.50
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 103.12
Number Outstanding (in shares)	75,710
Weighted Average Remaining Contractual Term	5 years 10 months 24 days
Number Exercisable (in shares)	33,210
Stock Options | $81.80 - 110.50 | Minimum
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 81.80
Stock Options | $81.80 - 110.50 | Maximum
Exercise price range of stock options
Exercise Price (in dollars per share)	110.50
Stock Options | $112.64 - 151.72
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 123.20
Number Outstanding (in shares)	457,608
Weighted Average Remaining Contractual Term	7 years
Number Exercisable (in shares)	34,908
Stock Options | $112.64 - 151.72 | Minimum
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 112.64
Stock Options | $112.64 - 151.72 | Maximum
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 151.72