EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net income	$ 31,757	$ 58,479	$ 202,039	$ 141,037
Denominator (shares in 000's):
Basic weighted average shares outstanding (in shares)	59,289,000	59,426,000	59,465,000	59,655,000
Effect of dilutive securities - stock options and awards (in shares)	766,000	592,000	703,000	547,000
Diluted weighted average shares outstanding (in shares)	60,055,000	60,018,000	60,168,000	60,202,000
Basic earnings per share (in dollars per share)	$ 0.54	$ 0.98	$ 3.40	$ 2.36
Diluted earnings per share (in dollars per share)	$ 0.53	$ 0.97	$ 3.36	$ 2.34
Anti-dilutive shares excluded from the computation of diluted earnings per share	2,126	557,198	150,254	547,329