STOCK-BASED PLANS (Details)-K (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 09, 2010
Weighted Average Exercise Price
Shares of common stock reserved for issuance				3,698,050
Significant assumptions used in Black-Scholes option-pricing model
Expiration period	10 years
Recognized compensation expense	$ 8,200,000	$ 5,700,000	$ 4,300,000
Maximum number of shares available for future grant	2,434,995
Minimum [Member]
Significant assumptions used in Black-Scholes option-pricing model
Exercisable period	5 years
Stock Options
Stock Options
Stock Options Outstanding at the beginning of the period (in shares)	965,440	861,940	712,640
Granted (in shares)	116,500	132,100	200,000
Forfeited (in shares)	(35,450)	(28,600)	(50,700)
Stock Options Outstanding at the end of the period (in shares)	1,046,490	965,440	861,940
Stock options exercisable at the end of the period (in shares)	400
Remaining unvested options outstanding and expected to vest (in shares)	1,024,077
Weighted Average Exercise Price
Stock Options Outstanding at the beginning of the period (in dollars per share)	$ 64.57	$ 59.17	$ 57.72
Granted (in dollars per share)	$ 144.26	$ 99.38	$ 64.19
Forfeited (in dollars per share)	$ 87.45	$ 62.40	$ 58.62
Stock Options Outstanding at the end of the period (in dollars per share)	$ 72.61	$ 64.57	$ 59.17
Stock options exercisable at the end of the period (in dollars per share)	$ 57.77
Stock options expected to vest at the end of the period (in dollars per share)	$ 72.33
Weighted average remaining contractual term of stock options outstanding	7 years
Weighted average remaining contractual term of stock options exercisable	2 years 6 months
Weighted average remaining contractual term of stock options expected to vest	7 years
Aggregate intrinsic value	61,986,678
Aggregate intrinsic value of stock options exercisable	29,060
Aggregate intrinsic value of stock options expected to vest	60,907,525
Exercise price range of stock options
Number Outstanding (in shares)	1,046,490
Exercise Price (in dollars per share)	$ 71.02
Weighted Average Remaining Contractual Term	7 years
Number Exercisable (in shares)	400
Significant assumptions used in Black-Scholes option-pricing model
Weighted average grant date fair value (in dollars per share)	$ 48.65	$ 28.04	$ 19.33
Weighted-average expected life of options	7 years 6 months	7 years 3 months 18 days	7 years 3 months 18 days
Weighted-average risk-free interest rate (as a percent)	2.20%	1.80%	1.40%
Weighted-average expected volatility (as a percent)	25.70%	22.00%	25.00%
Unamortized stock option expense	12,800,000
Weighted-average period for recognition of unamortized restricted stock expense	3 years
Stock Options | General and Administrative Expense [Member]
Significant assumptions used in Black-Scholes option-pricing model
Recognized compensation expense	$ 4,300,000	$ 3,500,000	$ 3,000,000
Stock Options | $46.49 - 55.82
Exercise price range of stock options
Number Outstanding (in shares)	63,500
Exercise Price (in dollars per share)	$ 51.26
Weighted Average Remaining Contractual Term	6 years 9 months 18 days
Stock Options | $46.49 - 55.82 | Minimum [Member]
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 46.49
Stock Options | $46.49 - 55.82 | Maximum [Member]
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
Number Outstanding (in shares)	580,400
Exercise Price (in dollars per share)	$ 57.95
Weighted Average Remaining Contractual Term	6 years 3 months 18 days
Number Exercisable (in shares)	400
Stock Options | $57.77 - 60.33 | Minimum [Member]
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 57.77
Stock Options | $57.77 - 60.33 | Maximum [Member]
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
Number Outstanding (in shares)	170,240
Exercise Price (in dollars per share)	$ 66.17
Weighted Average Remaining Contractual Term	7 years 3 months 18 days
Stock Options | $61.64 - 69.75 | Minimum [Member]
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 61.64
Stock Options | $61.64 - 69.75 | Maximum [Member]
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
Number Outstanding (in shares)	128,100
Exercise Price (in dollars per share)	$ 99.90
Weighted Average Remaining Contractual Term	8 years 6 months
Stock Options | $81.80 - 110.50 | Minimum [Member]
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 81.80
Stock Options | $81.80 - 110.50 | Maximum [Member]
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 110.50
Stock Options | $125.09 - 151.72
Exercise price range of stock options
Number Outstanding (in shares)	104,250
Exercise Price (in dollars per share)	$ 144.17
Weighted Average Remaining Contractual Term	9 years 4 months 24 days
Stock Options | $125.09 - 151.72 | Minimum [Member]
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 125.09
Stock Options | $125.09 - 151.72 | Maximum [Member]
Exercise price range of stock options
Exercise Price (in dollars per share)	$ 151.72