STOCK-BASED COMPENSATION - Stock Options Outstanding and Exercisable (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Options Outstanding
Options outstanding (shares) | shares	5,814
Weighted- Average Remaining Contractual Life in Years	6 years 1 month 6 days
Weighted-average exercise price (USD per share)	$ 62.97
Options Exercisable
Options exercisable (shares) | shares	3,592
Weighted- Average Remaining Contractual Life in Years	5 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 59.64
$20.01 to $30.00
Options Outstanding
Options outstanding (shares) | shares	30
Weighted- Average Remaining Contractual Life in Years	1 year 1 month 6 days
Weighted-average exercise price (USD per share)	$ 21.60
Options Exercisable
Options exercisable (shares) | shares	30
Weighted- Average Remaining Contractual Life in Years	1 year 1 month 6 days
Weighted-average exercise price (USD per share)	$ 21.60
$30.01 to $40.00
Options Outstanding
Options outstanding (shares) | shares	389
Weighted- Average Remaining Contractual Life in Years	2 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 32.30
Options Exercisable
Options exercisable (shares) | shares	389
Weighted- Average Remaining Contractual Life in Years	2 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 32.30
$40.01 to $50.00
Options Outstanding
Options outstanding (shares) | shares	1,541
Weighted- Average Remaining Contractual Life in Years	5 years 9 months 18 days
Weighted-average exercise price (USD per share)	$ 43.35
Options Exercisable
Options exercisable (shares) | shares	961
Weighted- Average Remaining Contractual Life in Years	5 years
Weighted-average exercise price (USD per share)	$ 44.26
$50.01 to $60.00
Options Outstanding
Options outstanding (shares) | shares	246
Weighted- Average Remaining Contractual Life in Years	3 years 2 months 12 days
Weighted-average exercise price (USD per share)	$ 59.85
Options Exercisable
Options exercisable (shares) | shares	244
Weighted- Average Remaining Contractual Life in Years	3 years 2 months 12 days
Weighted-average exercise price (USD per share)	$ 59.86
$60.01 to $70.00
Options Outstanding
Options outstanding (shares) | shares	1,173
Weighted- Average Remaining Contractual Life in Years	6 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 65.27
Options Exercisable
Options exercisable (shares) | shares	767
Weighted- Average Remaining Contractual Life in Years	6 years
Weighted-average exercise price (USD per share)	$ 65.62
$70.01 to $80.00
Options Outstanding
Options outstanding (shares) | shares	1,840
Weighted- Average Remaining Contractual Life in Years	7 years 4 months 24 days
Weighted-average exercise price (USD per share)	$ 75.33
Options Exercisable
Options exercisable (shares) | shares	822
Weighted- Average Remaining Contractual Life in Years	6 years 9 months 18 days
Weighted-average exercise price (USD per share)	$ 74.72
$80.01 to $90.00
Options Outstanding
Options outstanding (shares) | shares	500
Weighted- Average Remaining Contractual Life in Years	6 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 84.31
Options Exercisable
Options exercisable (shares) | shares	375
Weighted- Average Remaining Contractual Life in Years	6 years 3 months 18 days
Weighted-average exercise price (USD per share)	$ 84.31
Greater than $90.01
Options Outstanding
Options outstanding (shares) | shares	95
Weighted- Average Remaining Contractual Life in Years	9 years 1 month 6 days
Weighted-average exercise price (USD per share)	$ 148.30
Options Exercisable
Options exercisable (shares) | shares	4
Weighted- Average Remaining Contractual Life in Years	8 years 10 months 24 days
Weighted-average exercise price (USD per share)	$ 125.08
Minimum | $20.01 to $30.00
Options Exercisable
Exercise price range, lower limit (USD per share)	20.01
Minimum | $30.01 to $40.00
Options Exercisable
Exercise price range, lower limit (USD per share)	30.01
Minimum | $40.01 to $50.00
Options Exercisable
Exercise price range, lower limit (USD per share)	40.01
Minimum | $50.01 to $60.00
Options Exercisable
Exercise price range, lower limit (USD per share)	50.01
Minimum | $60.01 to $70.00
Options Exercisable
Exercise price range, lower limit (USD per share)	60.01
Minimum | $70.01 to $80.00
Options Exercisable
Exercise price range, lower limit (USD per share)	70.01
Minimum | $80.01 to $90.00
Options Exercisable
Exercise price range, lower limit (USD per share)	80.01
Minimum | Greater than $90.01
Options Exercisable
Exercise price range, lower limit (USD per share)	90.01
Maximum | $20.01 to $30.00
Options Exercisable
Exercise price range, upper limit (USD per share)	30
Maximum | $30.01 to $40.00
Options Exercisable
Exercise price range, upper limit (USD per share)	40
Maximum | $40.01 to $50.00
Options Exercisable
Exercise price range, upper limit (USD per share)	50
Maximum | $50.01 to $60.00
Options Exercisable
Exercise price range, upper limit (USD per share)	60.00
Maximum | $60.01 to $70.00
Options Exercisable
Exercise price range, upper limit (USD per share)	70.00
Maximum | $70.01 to $80.00
Options Exercisable
Exercise price range, upper limit (USD per share)	80.00
Maximum | $80.01 to $90.00
Options Exercisable
Exercise price range, upper limit (USD per share)	$ 90.00