NET INCOME PER SHARE (DILUTED SHARES TABLE) (DETAILS) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Shares used in basic earnings per share calculation	48,714	49,093	49,351	50,045	50,439	50,732	51,861	52,347	49,297	51,338	54,738
Effect of dilutive securities:
Stock options									413	417	378
Restricted stock units									392	489	424
Performance-based restricted stock units									0	0	0
Total effects of dilutive securities									805	906	802
Shares used in dilutive earnings per share calculation	49,514	49,940	50,111	50,973	51,465	51,678	52,628	53,217	50,102	52,244	55,540