Variable Interest Entities (Details) $ / shares in Units, $ in Thousands, shares in Millions		1 Months Ended				3 Months Ended		6 Months Ended		11 Months Ended
	Jan. 01, 2016 USD ($)	Jul. 31, 2015 USD ($)	May. 31, 2015 USD ($) $ / shares shares	Apr. 30, 2015 USD ($)	May. 31, 2014 USD ($) program	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	May. 04, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Variable Interest Entity [Line Items]
Payments to acquire IPO shares								$ 9,000	$ 0
Investment in Viking Therapeutics						$ 33,996		33,996			$ 0
Note receivable						5,547		5,547			0
Loss percentage recorded										100.00%
Gain on deconsolidation of Viking Therapeutics						28,190	$ 0	28,190	0
Equity in net losses from Viking Therapeutics						(870)	0	(870)	0
Net losses						23,564	1,592	24,318	3,688
Viking's Assets and Liabilities [Abstract]
Cash and cash equivalents						108,238	14,536	108,238	14,536		160,203	$ 11,639
Other current assets						1,801		1,801			1,842
Capitalized IPO expenses						0		0			2,268
Total current assets						196,725		196,725			186,419
Other assets						301		301			207
Total assets						304,762		304,762			258,029
Accounts payable						2,708		2,708			7,698
Accrued liabilities						5,629		5,629			4,866
Total current liabilities						17,949		17,949			22,779
Total liabilities						235,709		235,709			233,621
Viking
Variable Interest Entity [Line Items]
Number of programs licensed | program					5
Value of common stock issued upon IPO					$ 29,000
Contingencies for repayment of debt				$ 20,000
Period after close of IPO when debt becomes due				1 year
Viking's Assets and Liabilities [Abstract]
Cash and cash equivalents						0		0			756
Other current assets											18
Capitalized IPO expenses											2,268
Total current assets											3,042
Other assets											1
Total assets											3,043
Accounts payable						0		0			2,211
Accrued liabilities											77
Current portion of notes payable											334
Total current liabilities											2,622
Long-term portion of notes payable											2,331
Total liabilities											$ 4,953
Debt | Viking
Variable Interest Entity [Line Items]
Convertible loan facility					$ 2,500
Interest accrual rate, less than					5.00%
Repayment in equity percentage				200.00%
Metabasis Therapeutics
Viking's Assets and Liabilities [Abstract]
Contingent liability change in amount						6,400	$ (1,900)	5,300	$ 500
Metabasis Therapeutics | Forecast
Viking's Assets and Liabilities [Abstract]
Contingent liability change in amount	$ 2,600
IPO | Viking
Variable Interest Entity [Line Items]
Ownership after close of IPO (percent)				49.90%
Viking Therapeutics, Inc. [Member]
Variable Interest Entity [Line Items]
Investment in Viking Therapeutics										$ 34,900
Net losses						7,900		13,600
Viking's Assets and Liabilities [Abstract]
Total assets						22,300		22,300
Total liabilities						$ 4,900		$ 4,900
Subsequent Event | Metabasis Therapeutics
Viking's Assets and Liabilities [Abstract]
Contingent liability change in amount		$ (500)
Common Stock
Variable Interest Entity [Line Items]
IPO shares purchased by the Company (shares) | shares			1.1
Payments to acquire IPO shares			$ 9,000
IPO shares received pursuant to amended MLA (shares) | shares			3.7
Aggregate value of shares received under licensing agreement			$ 29,200
Equity interest in outstanding common stock of Viking (percent)						48.80%		48.80%
Common Stock | Viking Therapeutics, Inc. [Member]
Variable Interest Entity [Line Items]
IPO share price (USD per share) | $ / shares			$ 8
Common Stock | Viking Therapeutics, Inc. [Member] | IPO
Variable Interest Entity [Line Items]
Shares issued in IPO (shares) | shares			3.5
IPO share price (USD per share) | $ / shares			$ 8
IPO aggregate offering price			$ 27,600
Common Stock Received Pursuant to Master License Agreement [Member] | Metabasis Therapeutics
Viking's Assets and Liabilities [Abstract]
Contingent liability change in amount						$ (400)		$ (400)
Viking Therapeutics, Inc. [Member]
Variable Interest Entity [Line Items]
Note receivable						$ 5,500		$ 5,500		$ 5,500