SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Revision of Prior Period Financial Statements) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capital in excess of par value	$ 537,132	$ 545,025	$ 495,462	$ 498,702
Treasury stock	(256,503)	(1,024,444)	(270,052)	(1,026,117)
Stock option exercises & restricted stock vestings	60,235	48,479
Total Stockholders' Equity	$ 1,258,592	1,127,690	$ 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		46,799
Treasury stock		1,673
Total Stockholders' Equity		48,479
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capital in excess of par value		555,307		507,313
Treasury stock		(1,034,726)		(1,034,728)
Total Stockholders' Equity		1,127,690		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		48,470
Treasury stock		2
Total Stockholders' Equity		48,479
Reissuance of incorrectly accounted treasury shares | Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capital in excess of par value		(10,282)		(8,611)
Treasury stock		10,282		$ 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		(1,671)
Treasury stock		$ 1,671