CAPITAL STOCK - OPTION ACTIVITY (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate (as a percent)	1.41%	1.21%	0.75%
Expected lives (in years)	3 years 4 months 21 days	3 years 4 months 24 days	3 years 4 months 24 days
Expected volatility (as a percent)	41.00%	43.00%	46.00%
Expected dividend rate (as a percent)	0.00%	0.00%	0.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period	1,074,251	1,321,232	1,245,161
Granted at Market	146,446	134,800	275,654
Canceled	(28,440)	(218,926)	(166,286)
Exercised	(251,647)	(162,855)	(33,297)
Outstanding at end of period	940,610	1,074,251	1,321,232
Exercisable at end of period	621,559	729,175	939,458
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding at beginning of period (in dollars per share)	$ 10.110	$ 10.386	$ 11.054
Granted at Market (in dollars per share)	36.904	16.398	7.532
Cancelled (in dollars per share)	10.080	17.786	11.437
Exercised (in dollars per share)	10.559	7.234	6.488
Outstanding at ending of period (in dollars per share)	14.163	10.110	10.386
Exercisable at end of period (in dollars per share)	$ 10.269	$ 9.800	$ 11.556
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate (as a percent)	0.27%	0.23%	0.21%
Expected lives (in years)	1 year 2 months 18 days	1 year 3 months 18 days	1 year 3 months 18 days
Expected volatility (as a percent)	36.00%	34.00%	34.00%
Expected dividend rate (as a percent)	0.00%	0.00%	0.00%