CAPITAL STOCK - OPTION ACTIVITY (Details) - $ / shares		12 Months Ended
	Apr. 16, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate (as a percent)		3.64%	1.62%	2.66%
Expected lives (in years)		5 years 3 months 18 days	4 years 8 months 12 days	4 years 10 months 24 days
Expected volatility (as a percent)		46.00%	40.00%	40.00%
Expected dividend rate (as a percent)		0.00%	0.00%	0.00%
Stock options and restricted shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period		536,315
Granted at market		83,250
Forfeited		(42,307)
Expired		(28,691)
Exercised		(84,335)
Outstanding at end of period		464,232	536,315
Exercisable at end of period		291,334
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)		$ 54.86
Granted at Market (in dollars per share)		69.27
Forfeited (in dollars per share)		76.24
Expired (in dollars per share)		69.25
Exercised (in dollars per share)		40.64
Outstanding at ending of period (in dollars per share)		57.18	$ 54.86
Exercisable at end of period (in dollars per share)		$ 46.53
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Forfeited		(20,000)
Exercised		0
Outstanding at end of period		220,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Granted at Market (in dollars per share)	$ 60.94	$ 25.04
Outstanding at ending of period (in dollars per share)		$ 60.94