FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS - SCHEDULE OF ASSETS AND LIABILITIES MEASURED AT FAIR VALUE ON A RECURRING BASIS (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets:
Marketable securities	$ 39,200	$ 160,648
Fair Value on a Recurring Basis
Assets:
Total	1,080,096	780,563
Liabilities:
Contingent consideration arrangements	(33,873)	(30,140)
Fair Value on a Recurring Basis | Money Market Funds
Assets:
Cash and cash equivalents	601,848	174,720
Fair Value on a Recurring Basis | Time Deposits
Assets:
Cash and cash equivalents	125,038	388,801
Fair Value on a Recurring Basis | Commercial Paper
Assets:
Cash and cash equivalents	302,418	42,914
Fair Value on a Recurring Basis | Corporate Debt Securities
Assets:
Marketable securities	27,578	159,197
Fair Value on a Recurring Basis | Equity Security
Assets:
Marketable securities	11,622	1,451
Long-term investments	7,542	7,410
Fair Value on a Recurring Basis | Auction Rate Security
Assets:
Long-term investments	4,050	6,070
Fair Value on a Recurring Basis | Level 1
Assets:
Total	621,012	183,581
Liabilities:
Contingent consideration arrangements	0	0
Fair Value on a Recurring Basis | Level 1 | Money Market Funds
Assets:
Cash and cash equivalents	601,848	174,720
Fair Value on a Recurring Basis | Level 1 | Time Deposits
Assets:
Cash and cash equivalents	0	0
Fair Value on a Recurring Basis | Level 1 | Commercial Paper
Assets:
Cash and cash equivalents	0	0
Fair Value on a Recurring Basis | Level 1 | Corporate Debt Securities
Assets:
Marketable securities	0	0
Fair Value on a Recurring Basis | Level 1 | Equity Security
Assets:
Marketable securities	11,622	1,451
Long-term investments	7,542	7,410
Fair Value on a Recurring Basis | Level 1 | Auction Rate Security
Assets:
Long-term investments	0	0
Fair Value on a Recurring Basis | Level 2
Assets:
Total	455,034	590,912
Liabilities:
Contingent consideration arrangements	0	0
Fair Value on a Recurring Basis | Level 2 | Money Market Funds
Assets:
Cash and cash equivalents	0	0
Fair Value on a Recurring Basis | Level 2 | Time Deposits
Assets:
Cash and cash equivalents	125,038	388,801
Fair Value on a Recurring Basis | Level 2 | Commercial Paper
Assets:
Cash and cash equivalents	302,418	42,914
Fair Value on a Recurring Basis | Level 2 | Corporate Debt Securities
Assets:
Marketable securities	27,578	159,197
Fair Value on a Recurring Basis | Level 2 | Equity Security
Assets:
Marketable securities	0	0
Long-term investments	0	0
Fair Value on a Recurring Basis | Level 2 | Auction Rate Security
Assets:
Long-term investments	0	0
Fair Value on a Recurring Basis | Level 3
Assets:
Total	4,050	6,070
Liabilities:
Contingent consideration arrangements	(33,873)	(30,140)
Fair Value on a Recurring Basis | Level 3 | Money Market Funds
Assets:
Cash and cash equivalents	0	0
Fair Value on a Recurring Basis | Level 3 | Time Deposits
Assets:
Cash and cash equivalents	0	0
Fair Value on a Recurring Basis | Level 3 | Commercial Paper
Assets:
Cash and cash equivalents	0	0
Fair Value on a Recurring Basis | Level 3 | Corporate Debt Securities
Assets:
Marketable securities	0	0
Fair Value on a Recurring Basis | Level 3 | Equity Security
Assets:
Marketable securities	0	0
Long-term investments	0	0
Fair Value on a Recurring Basis | Level 3 | Auction Rate Security
Assets:
Long-term investments	$ 4,050	$ 6,070