FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Assets:
Marketable securities	$ 39,543	$ 6,004
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total Assets	441,850	715,014
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Assets:
Cash equivalents:	426,050	698,307
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Assets:
Marketable securities	5,582	4,996
Long-term investments:	10,218	11,711
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Total Assets	272,589	45,333
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Cash equivalents:	184,005	12,000
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Time deposits
Assets:
Cash equivalents:	54,623	32,325
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Corporate debt securities
Assets:
Marketable securities	33,961	1,008
Fair value on a recurring basis | Significant Unobservable Inputs (Level 3)
Assets:
Total Assets	9,150	8,920
Liabilities:
Contingent consideration arrangement	(48,758)	(45,828)
Fair value on a recurring basis | Significant Unobservable Inputs (Level 3) | Auction rate security
Assets:
Long-term investments:	9,150	8,920
Fair value on a recurring basis | Fair value
Assets:
Total Assets	723,589	769,267
Liabilities:
Contingent consideration arrangement	(48,758)	(45,828)
Fair value on a recurring basis | Fair value | Money market funds
Assets:
Cash equivalents:	426,050	698,307
Fair value on a recurring basis | Fair value | Commercial paper
Assets:
Cash equivalents:	184,005	12,000
Fair value on a recurring basis | Fair value | Time deposits
Assets:
Cash equivalents:	54,623	32,325
Fair value on a recurring basis | Fair value | Corporate debt securities
Assets:
Marketable securities	33,961	1,008
Fair value on a recurring basis | Fair value | Equity securities
Assets:
Marketable securities	5,582	4,996
Long-term investments:	10,218	11,711
Fair value on a recurring basis | Fair value | Auction rate security
Assets:
Long-term investments:	$ 9,150	$ 8,920