FAIR VALUE MEASUREMENTS (Details ) - Recurring basis - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Level 1
Fair value
Assets, Total	$ 189,827	$ 189,030
Level 2
Fair value
Assets, Total	401,713	386,933
Level 3
Fair value
Assets, Total	62,981
Total
Fair value
Assets, Total	654,521	575,963
U.S. government and agency debt securities | Level 1
Fair value
Assets, Total	189,827	189,030
U.S. government and agency debt securities | Level 2
Fair value
Assets, Total	130,114	137,623
U.S. government and agency debt securities | Total
Fair value
Assets, Total	319,941	326,653
Corporate debt securities | Level 2
Fair value
Assets, Total	240,589	201,963
Corporate debt securities | Total
Fair value
Assets, Total	240,589	201,963
International government agency debt securities | Level 2
Fair value
Assets, Total	31,010	47,347
International government agency debt securities | Total
Fair value
Assets, Total	31,010	$ 47,347
Contingent Consideration | Level 3
Fair value
Assets, Total	60,300
Contingent Consideration | Total
Fair value
Assets, Total	60,300
Equity securities | Level 3
Fair value
Assets, Total	2,681
Equity securities | Total
Fair value
Assets, Total	$ 2,681