Fair Value Measurements (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Aug. 31, 2014
2019 convertible senior notes
Liabilities:
Principal amount outstanding	$ 245,000,000	$ 245,000,000
2019 convertible senior notes | Senior Notes
Liabilities:
Principal amount outstanding			$ 245,000,000.0
Estimated fair value of debt	365,100,000
Recurring
Assets:
Assets, fair value	152,700,000	126,187,000
Liabilities:
Liabilities, fair value	3,508,000	3,388,000
Recurring | Current contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	111,000	101,000
Recurring | Long-term contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	1,503,000	1,503,000
Recurring | Long-term contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	1,532,000	1,413,000
Recurring | Liability for amounts owed to former licensees
Liabilities:
Liabilities, fair value	362,000	371,000
Recurring | Short-term Investments [Member]
Assets:
Assets, fair value	148,733,000	122,296,000
Recurring | Note receivable Viking Therapeutics, Inc.
Assets:
Assets, fair value	$ 3,207,000	3,207,000
Liabilities:
Volatility of common stock	75.00%
Recurring | Investment in warrants
Assets:
Assets, fair value	$ 760,000	684,000
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Assets, fair value	3,170,000	3,738,000
Liabilities:
Liabilities, fair value	362,000	371,000
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) | Long-term contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	0	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) | Liability for amounts owed to former licensees
Liabilities:
Liabilities, fair value	362,000	371,000
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments [Member]
Assets:
Assets, fair value	2,410,000	3,054,000
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Note receivable Viking Therapeutics, Inc.
Assets:
Assets, fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Investment in warrants
Assets:
Assets, fair value	760,000	684,000
Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Assets, fair value	146,323,000	119,242,000
Liabilities:
Liabilities, fair value	1,532,000	1,413,000
Recurring | Significant Other Observable Inputs (Level 2) | Current contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Long-term contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Long-term contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	1,532,000	1,413,000
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) | Short-term Investments [Member]
Assets:
Assets, fair value	146,323,000	119,242,000
Recurring | Significant Other Observable Inputs (Level 2) | Note receivable Viking Therapeutics, Inc.
Assets:
Assets, fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Investment in warrants
Assets:
Assets, fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Assets, fair value	3,207,000	3,207,000
Liabilities:
Liabilities, fair value	1,614,000	1,604,000
Recurring | Significant Unobservable Inputs (Level 3) | Current contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	111,000	101,000
Recurring | Significant Unobservable Inputs (Level 3) | Long-term contingent liabilities-CyDex
Liabilities:
Liabilities, fair value	1,503,000	1,503,000
Recurring | Significant Unobservable Inputs (Level 3) | Long-term contingent liabilities-Metabasis
Liabilities:
Liabilities, fair value	0	0
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) | Short-term Investments [Member]
Assets:
Assets, fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Note receivable Viking Therapeutics, Inc.
Assets:
Assets, fair value	3,207,000	3,207,000
Recurring | Significant Unobservable Inputs (Level 3) | Investment in warrants
Assets:
Assets, fair value	$ 0	$ 0