FAIR VALUE MEASUREMENTS (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Assets:
Marketable securities:	$ 5,814	$ 20,604
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total Assets	405,715	583,511
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Treasury and government agency money market funds
Assets:
Cash equivalents:		545,290
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Assets:
Cash equivalents:	373,770
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Assets:
Marketable securities:	4,793	6,977
Fair value on a recurring basis | Quoted Market Prices in Active Markets for Identical Assets (Level 1) | Long-term marketable equity securities
Assets:
Long-term investments:	27,152	31,244
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Total Assets	184,851	25,621
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Cash equivalents:	89,987
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Time deposits
Assets:
Cash equivalents:	93,843	11,994
Fair value on a recurring basis | Significant Other Observable Inputs (Level 2) | Corporate debt securities
Assets:
Marketable securities:	1,021	13,627
Fair value on a recurring basis | Significant Unobservable Inputs (Level 3)
Assets:
Total Assets	8,580	8,100
Liabilities:
Contingent consideration arrangement	(42,295)
Fair value on a recurring basis | Significant Unobservable Inputs (Level 3) | Auction rate security
Assets:
Long-term investments:	8,580	8,100
Fair value on a recurring basis | Total Fair Value Measurements
Assets:
Total Assets	599,146	617,232
Liabilities:
Contingent consideration arrangement	(42,295)
Fair value on a recurring basis | Total Fair Value Measurements | Treasury and government agency money market funds
Assets:
Cash equivalents:		545,290
Fair value on a recurring basis | Total Fair Value Measurements | Money market funds
Assets:
Cash equivalents:	373,770
Fair value on a recurring basis | Total Fair Value Measurements | Commercial paper
Assets:
Cash equivalents:	89,987
Fair value on a recurring basis | Total Fair Value Measurements | Time deposits
Assets:
Cash equivalents:	93,843	11,994
Fair value on a recurring basis | Total Fair Value Measurements | Corporate debt securities
Assets:
Marketable securities:	1,021	13,627
Fair value on a recurring basis | Total Fair Value Measurements | Equity securities
Assets:
Marketable securities:	4,793	6,977
Fair value on a recurring basis | Total Fair Value Measurements | Auction rate security
Assets:
Long-term investments:	8,580	8,100
Fair value on a recurring basis | Total Fair Value Measurements | Long-term marketable equity securities
Assets:
Long-term investments:	$ 27,152	$ 31,244