SHAREHOLDERS' EQUITY (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Jul. 24, 2020	Feb. 28, 2019	Feb. 28, 2018	May 31, 2017
Calculation of weighted average common shares
Weighted average common shares, basic	13,268	13,033	13,194	12,992
Effect of dilutive securities
Effect of stock options (in shares)	0	0	452	0
Effect of dilutive share awards (in shares)	0	0	96	0
Effect of Convertible Senior Notes (in shares)	0	0	55	0
Weighted average common shares, diluted	13,268	13,033	13,797	12,992
Antidilutive securities excluded from computation of earnings per share (in shares)	400	1,300		1,100
Common stock repurchases
Value of common stock authorized to be repurchased							$ 150.0	$ 100.0
Remaining authorized repurchase amount	$ 179.7		$ 179.7
2025 Convertible Notes
Effect of dilutive securities
Stated interest rate	0.50%		0.50%		0.50%
2025 Convertible Notes | Convertible Debt
Effect of dilutive securities
Stated interest rate					0.50%	0.50%
2022 Convertible Notes
Effect of dilutive securities
Stated interest rate	0.625%		0.625%		0.625%
2022 Convertible Notes | Convertible Debt
Effect of dilutive securities
Stated interest rate					0.625%				0.625%
Option
Effect of dilutive securities
Antidilutive securities excluded from computation of earnings per share (in shares)	900	100	400	200
Restricted Stock Units (RSUs)
Effect of dilutive securities
Antidilutive securities excluded from computation of earnings per share (in shares)	200		100