FAIR VALUE MEASUREMENTS (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
Assets
Short-term investments	$ 438,282,000		$ 470,348,000
Liabilities
Contingent consideration	161,360,000
Excluded portion
Liabilities
Cash	232,200,000
Certificate of deposit excluded and recorded at cost	15,000,000		17,200,000
Optimer CVRs
Liabilities
Contingent consideration			68,600,000
Bank deposits
Assets
Short-term investments	60,200,000		40,000,000
U.S. Treasury securities
Assets
Short-term investments	70,185,000		67,650,000
Corporate and municipal notes
Assets
Short-term investments	307,897,000		362,698,000
Recurring Basis | Level 1
Assets
Total assets	70,185,000
Liabilities
Total liabilities	6,094,000
Recurring Basis | Level 1 | Optimer CVRs
Liabilities
Contingent consideration	6,094,000
Recurring Basis | Level 1 | Other
Liabilities
Contingent consideration	0
Recurring Basis | Level 1 | Bank deposits
Assets
Short-term investments	0	[1]
Recurring Basis | Level 1 | U.S. Treasury securities
Assets
Short-term investments	70,185,000	[1]
Recurring Basis | Level 1 | Corporate and municipal notes
Assets
Cash and cash equivalents	0	[2]
Short-term investments	0	[1]
Recurring Basis | Level 2
Assets
Total assets	369,599,000
Liabilities
Total liabilities	0
Recurring Basis | Level 2 | Optimer CVRs
Liabilities
Contingent consideration	0
Recurring Basis | Level 2 | Other
Liabilities
Contingent consideration	0
Recurring Basis | Level 2 | Bank deposits
Assets
Short-term investments	60,200,000	[1]
Recurring Basis | Level 2 | U.S. Treasury securities
Assets
Short-term investments	0	[1]
Recurring Basis | Level 2 | Corporate and municipal notes
Assets
Cash and cash equivalents	1,502,000	[2]
Short-term investments	307,897,000	[1]
Recurring Basis | Level 3
Assets
Total assets	0
Liabilities
Total liabilities	161,360,000
Recurring Basis | Level 3 | Optimer CVRs
Liabilities
Contingent consideration	0
Recurring Basis | Level 3 | Other
Liabilities
Contingent consideration	161,360,000
Recurring Basis | Level 3 | Bank deposits
Assets
Short-term investments	0	[1]
Recurring Basis | Level 3 | U.S. Treasury securities
Assets
Short-term investments	0	[1]
Recurring Basis | Level 3 | Corporate and municipal notes
Assets
Cash and cash equivalents	0	[2]
Short-term investments	0	[1]
Recurring Basis | Total Fair Value
Assets
Total assets	439,784,000
Liabilities
Total liabilities	167,454,000
Recurring Basis | Total Fair Value | Optimer CVRs
Liabilities
Contingent consideration	6,094,000
Recurring Basis | Total Fair Value | Other
Liabilities
Contingent consideration	161,360,000
Recurring Basis | Total Fair Value | Bank deposits
Assets
Short-term investments	60,200,000	[1]
Recurring Basis | Total Fair Value | U.S. Treasury securities
Assets
Short-term investments	70,185,000	[1]
Recurring Basis | Total Fair Value | Corporate and municipal notes
Assets
Cash and cash equivalents	1,502,000	[2]
Short-term investments	$ 307,897,000	[1]

[1] Excludes certificates of deposit of $15.0 million recorded at cost as of September 30, 2014.

[2] Excludes $232.2 million of cash as of September 30, 2014.