Fair Value Measurements (Details) - USD ($)	9 Months Ended
	Sep. 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	318,600,000
Principal amount outstanding			$ 245,000,000.0
Recurring
Assets:
Assets, fair value	163,771,000	76,716,000
Liabilities:
Liabilities, fair value	16,786,000	16,244,000
Recurring | Current contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	5,018,000	6,796,000
Recurring | Current contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	2,602,000
Recurring | Current co-promote termination liability
Liabilities:
Liabilities, fair value		322,000
Recurring | Long-term contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	2,120,000	3,652,000
Recurring | Long-term contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	5,469,000	4,701,000
Recurring | Liability for amounts owed to former licensees
Liabilities:
Liabilities, fair value	1,577,000	773,000
Recurring | Cash Equivalents
Assets:
Assets, fair value	62,637,000	69,261,000
Recurring | Short-term investments
Assets:
Assets, fair value	$ 95,587,000	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	7,543,000	7,133,000
Liabilities:
Liabilities, fair value	1,577,000	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	1,577,000	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	7,543,000	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	150,681,000	69,261,000
Liabilities:
Liabilities, fair value	4,722,000	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	2,602,000
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	2,120,000	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	62,637,000	69,261,000
Recurring | Significant Other Observable Inputs (Level 2) | Short-term investments
Assets:
Assets, fair value	88,044,000	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	10,487,000	11,819,000
Recurring | Significant Unobservable Inputs (Level 3) | Current contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	5,018,000	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	5,469,000	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.
Liabilities:
Market value of investment in Viking	$ 28,000,000