Fair Value Measurements (Details) - USD ($)	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Aug. 31, 2014
2019 convertible senior notes
Liabilities:
Principal amount outstanding	$ 245,000,000	$ 245,000,000
2019 convertible senior notes | Senior Notes
Liabilities:
Estimated fair value of debt	353,600,000
Principal amount outstanding			$ 245,000,000.0
Recurring
Assets:
Assets, fair value	166,995,000	76,716,000
Liabilities:
Liabilities, fair value	20,441,000	16,244,000
Recurring | Current contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	4,597,000	6,796,000
Recurring | Current contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	3,077,000
Recurring | Current co-promote termination liability
Liabilities:
Liabilities, fair value		322,000
Recurring | Long-term contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	5,316,000	3,652,000
Recurring | Long-term contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	5,773,000	4,701,000
Recurring | Liability for amounts owed to former licensees
Liabilities:
Liabilities, fair value	1,678,000	773,000
Recurring | Cash Equivalents
Assets:
Assets, fair value	88,077,000	69,261,000
Recurring | Short-term investments
Assets:
Assets, fair value	$ 73,371,000	7,133,000
Recurring | Note receivable Viking Therapeutics, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated volatility of common stock	50.00%
Assets:
Assets, fair value	$ 5,547,000
Recurring | Current co-promote termination payments receivable
Assets:
Assets, fair value		322,000
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Assets, fair value	13,262,000	7,133,000
Liabilities:
Liabilities, fair value	1,678,000	773,000
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Current contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Current contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Current co-promote termination liability
Liabilities:
Liabilities, fair value		0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Liability for amounts owed to former licensees
Liabilities:
Liabilities, fair value	1,678,000	773,000
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash Equivalents
Assets:
Assets, fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments
Assets:
Assets, fair value	13,262,000	7,133,000
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Note receivable Viking Therapeutics, Inc.
Assets:
Assets, fair value	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Current co-promote termination payments receivable
Assets:
Assets, fair value		0
Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Assets, fair value	148,186,000	69,261,000
Liabilities:
Liabilities, fair value	8,393,000	3,652,000
Recurring | Significant Other Observable Inputs (Level 2) | Current contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Current contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	3,077,000
Recurring | Significant Other Observable Inputs (Level 2) | Current co-promote termination liability
Liabilities:
Liabilities, fair value		0
Recurring | Significant Other Observable Inputs (Level 2) | Long-term contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	5,316,000	3,652,000
Recurring | Significant Other Observable Inputs (Level 2) | Long-term contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Liability for amounts owed to former licensees
Liabilities:
Liabilities, fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Cash Equivalents
Assets:
Assets, fair value	88,077,000	69,261,000
Recurring | Significant Other Observable Inputs (Level 2) | Short-term investments
Assets:
Assets, fair value	60,109,000	0
Recurring | Significant Other Observable Inputs (Level 2) | Note receivable Viking Therapeutics, Inc.
Assets:
Assets, fair value	0
Recurring | Significant Other Observable Inputs (Level 2) | Current co-promote termination payments receivable
Assets:
Assets, fair value		0
Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Assets, fair value	5,547,000	322,000
Liabilities:
Liabilities, fair value	10,370,000	11,819,000
Recurring | Significant Unobservable Inputs (Level 3) | Current contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	4,597,000	6,796,000
Recurring | Significant Unobservable Inputs (Level 3) | Current contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	0
Recurring | Significant Unobservable Inputs (Level 3) | Current co-promote termination liability
Liabilities:
Liabilities, fair value		322,000
Recurring | Significant Unobservable Inputs (Level 3) | Long-term contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Long-term contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	5,773,000	4,701,000
Recurring | Significant Unobservable Inputs (Level 3) | Liability for amounts owed to former licensees
Liabilities:
Liabilities, fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Cash Equivalents
Assets:
Assets, fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Short-term investments
Assets:
Assets, fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Note receivable Viking Therapeutics, Inc.
Assets:
Assets, fair value	5,547,000
Recurring | Significant Unobservable Inputs (Level 3) | Current co-promote termination payments receivable
Assets:
Assets, fair value		$ 322,000
Viking Therapeutics, Inc. [Member]
Liabilities:
Market value of investment in Viking	$ 34,200,000