NET INCOME PER SHARE (DILUTED SHARES TABLE) (Details) - shares shares in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Shares used in basic earnings per share calculation	46,487	46,481	46,318	46,203	46,193	46,172	46,016	45,871	46,373	46,064	45,826
Effect of dilutive securities:
Stock options										6	10
Restricted stock units									349	314	536
Performance-based restricted stock units									36	1	10
Total effects of dilutive securities									385	321	556
Shares used in dilutive earnings per share calculation	46,831	46,768	46,684	46,590	46,390	46,316	46,401	46,452	46,758	46,385	46,382