SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Revision of Prior Period Financial Statements) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capital in excess of par value	$ 519,627	$ 530,874	$ 495,462	$ 498,702
Treasury stock	(259,519)	(1,025,038)	(270,052)	(1,026,117)
Stock option exercises & restricted stock vestings	35,481	33,256
Total Stockholders' Equity	$ 1,267,654	1,026,798	$ 1,149,706	1,103,916
Stock option exercises & restricted stock vestings
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capital in excess of par value		32,172
Treasury stock		1,079
Total Stockholders' Equity		33,256
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capital in excess of par value		540,563		507,313
Treasury stock		(1,034,727)		(1,034,728)
Total Stockholders' Equity		1,026,798		1,103,916
As Previously Reported | Stock option exercises & restricted stock vestings
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capital in excess of par value		33,250
Treasury stock		1
Total Stockholders' Equity		33,256
Reissuance of incorrectly accounted treasury shares | Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capital in excess of par value		(9,689)		(8,611)
Treasury stock		9,689		$ 8,611
Reissuance of incorrectly accounted treasury shares | Adjustment | Stock option exercises & restricted stock vestings
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capital in excess of par value		(1,078)
Treasury stock		$ 1,078