CAPITAL STOCK- SUMMARY OF INFORMATION BY EXERCISE PRICE RANGE (Details)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
$4.50 - $7.36
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options Outstanding at December 31, 2018 | shares	167,737
Weighted Average Remaining Contractual Life in Years	3 years 7 months 10 days
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 6.565
Number of Options Exercisable at December 31, 2018 | shares	167,737
Weighted Average Remaining Contractual Life in Years	3 years 7 months 10 days
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 6.565
Exercise price, lower range limit	4.50
Exercise price, upper range limit	$ 7.36
$7.37 - $32.21
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options Outstanding at December 31, 2018 | shares	128,465
Weighted Average Remaining Contractual Life in Years	5 years 3 months 5 days
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 15.777
Number of Options Exercisable at December 31, 2018 | shares	127,261
Weighted Average Remaining Contractual Life in Years	5 years 2 months 30 days
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 15.631
Exercise price, lower range limit	7.37
Exercise price, upper range limit	$ 32.21
$32.22 - $62.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options Outstanding at December 31, 2018 | shares	75,972
Weighted Average Remaining Contractual Life in Years	7 years 10 days
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 39.745
Number of Options Exercisable at December 31, 2018 | shares	54,133
Weighted Average Remaining Contractual Life in Years	7 years 15 days
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 39.647
Exercise price, lower range limit	32.22
Exercise price, upper range limit	$ 62.50
$62.51 - $69.77
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options Outstanding at December 31, 2018 | shares	130,000
Weighted Average Remaining Contractual Life in Years	9 years 2 months 6 days
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 69.770
Number of Options Exercisable at December 31, 2018 | shares	0
Weighted Average Remaining Contractual Life in Years	0 days
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 0.000
Exercise price, lower range limit	62.51
Exercise price, upper range limit	$ 69.77
$69.78 - $108.25
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options Outstanding at December 31, 2018 | shares	118,379
Weighted Average Remaining Contractual Life in Years	8 years 4 months 25 days
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 85.020
Number of Options Exercisable at December 31, 2018 | shares	37,045
Weighted Average Remaining Contractual Life in Years	8 years 1 month 15 days
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 79.793
Exercise price, lower range limit	69.78
Exercise price, upper range limit	$ 108.25
$4.50 - $108.25
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options Outstanding at December 31, 2018 | shares	620,553
Weighted Average Remaining Contractual Life in Years	6 years 5 months 12 days
Options Outstanding - Weighted Average Exercise Price (in dollars per share)	$ 40.741
Number of Options Exercisable at December 31, 2018 | shares	386,176
Weighted Average Remaining Contractual Life in Years	5 years 23 days
Options Exercisable - Weighted Average Exercise Price (in dollars per share)	$ 21.214
Exercise price, lower range limit	4.50
Exercise price, upper range limit	$ 108.25