Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details) $ / shares in Units, shares in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017 USD ($) program $ / shares shares	Dec. 31, 2016 USD ($)	May 08, 2017 USD ($)	Aug. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Working capital deficit	$ 28,700,000
Equity component of currently redeemable convertible notes	24,293,000	$ 29,563,000
Consecutive trading days		50 days
Discrete income tax benefit	$ 900,000
Note receivable, interest and principal reduction per dollar of value	0.50
2019 convertible senior notes
Property, Plant and Equipment [Line Items]
Principal amount outstanding	$ 245,000,000	$ 245,000,000
2019 convertible senior notes | Senior Notes
Property, Plant and Equipment [Line Items]
Principal amount outstanding				$ 245,000,000.0
Interest rate (percent)				0.75%
Retained Earnings | Accounting Standards Update 2016-09
Property, Plant and Equipment [Line Items]
Cumulative effect of new accounting principle in period of adoption		17,900,000
Retained Earnings | Accounting Standards Update 2016-09, Forfeiture Rate Component
Property, Plant and Equipment [Line Items]
Cumulative effect of new accounting principle in period of adoption		300,000
Recurring
Property, Plant and Equipment [Line Items]
Assets, fair value	116,219,000	126,187,000
Recurring | Investment in warrants
Property, Plant and Equipment [Line Items]
Assets, fair value	608,000	684,000
Recurring | Note receivable Viking Therapeutics, Inc.
Property, Plant and Equipment [Line Items]
Assets, fair value	3,207,000	3,207,000
Recurring | Fair Value, Inputs, Level 1
Property, Plant and Equipment [Line Items]
Assets, fair value	2,946,000	3,738,000
Recurring | Fair Value, Inputs, Level 1 | Investment in warrants
Property, Plant and Equipment [Line Items]
Assets, fair value	608,000	684,000
Recurring | Fair Value, Inputs, Level 1 | Note receivable Viking Therapeutics, Inc.
Property, Plant and Equipment [Line Items]
Assets, fair value	0	0
Recurring | Fair Value, Inputs, Level 3
Property, Plant and Equipment [Line Items]
Assets, fair value	3,207,000	3,207,000
Recurring | Fair Value, Inputs, Level 3 | Investment in warrants
Property, Plant and Equipment [Line Items]
Assets, fair value	0	0
Recurring | Fair Value, Inputs, Level 3 | Note receivable Viking Therapeutics, Inc.
Property, Plant and Equipment [Line Items]
Assets, fair value	$ 3,207,000	$ 3,207,000
Viking Therapeutics, Inc.
Property, Plant and Equipment [Line Items]
Equity method investment, ownership (percent)	22.70%
Market value of investment in Viking	$ 6,800,000
Outstanding warrants to purchase shares of Viking's common stock (shares) | shares	1.5
Warrant exercise price (USD per share) | $ / shares	$ 1.50
Number of programs licensed to Viking | program	5
Note receivable, stated interest rate (percent)	2.50%
Note Receivable, Cash Repayment Due			$ 200,000