FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Assets:
Marketable securities:	$ 7,775,000	$ 20,604,000
Long-term marketable equity securities
Gross unrealized losses	0	0
Gross unrealized gain	6,772,000	6,996,000
Equity securities
Long-term marketable equity securities
Cost basis	42,100,000	42,100,000
Gross unrealized losses	500,000	10,800,000
Gross unrealized gain	1,400,000
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total Assets	370,684,000	583,511,000
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Assets:
Cash equivalents:	320,989,000	545,290,000
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Equity security
Assets:
Marketable securities:	6,761,000	6,977,000
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Assets:
Long-term investments:	42,934,000	31,244,000
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Total Assets	211,465,000	25,621,000
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Cash equivalents:	109,629,000
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Time deposits
Assets:
Cash equivalents:	100,822,000	11,994,000
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Corporate debt securities
Assets:
Marketable securities:	1,014,000	13,627,000
Fair value on a recurring basis | Significant Unobservable Inputs (Level 3)
Assets:
Total Assets	8,760,000	8,100,000
Liabilities:
Contingent consideration arrangement	(46,912,000)
Fair value on a recurring basis | Significant Unobservable Inputs (Level 3) | Auction rate security
Assets:
Long-term investments:	8,760,000	8,100,000
Fair value on a recurring basis | Fair Value
Assets:
Total Assets	590,909,000	617,232,000
Liabilities:
Contingent consideration arrangement	(46,912,000)
Fair value on a recurring basis | Fair Value | Money market funds
Assets:
Cash equivalents:	320,989,000	545,290,000
Fair value on a recurring basis | Fair Value | Commercial paper
Assets:
Cash equivalents:	109,629,000
Fair value on a recurring basis | Fair Value | Time deposits
Assets:
Cash equivalents:	100,822,000	11,994,000
Fair value on a recurring basis | Fair Value | Corporate debt securities
Assets:
Marketable securities:	1,014,000	13,627,000
Fair value on a recurring basis | Fair Value | Equity security
Assets:
Marketable securities:	6,761,000	6,977,000
Fair value on a recurring basis | Fair Value | Auction rate security
Assets:
Long-term investments:	8,760,000	8,100,000
Fair value on a recurring basis | Fair Value | Equity securities
Assets:
Long-term investments:	$ 42,934,000	$ 31,244,000