Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2017

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

Financial assets and liabilities measured at fair value on a recurring basis as were as follows (in thousands):



	Level 1		Level 2		Level 3
Assets as of September 30, 2017:
Short-term investments	$	57,487	$	—	$	—
Investment at fair value (Note 5)	—		—		208,796
Total recurring fair value measurements⁽¹⁾	$	57,487	$	—	$	208,796

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

A reconciliation of the activity for fair value measurements categorized within Level 3 for the nine months ended September 30, 2017 is as follows (in thousands):



	Investment at Fair Value
	Common Stock		Warrants		Total
Opening balance as of January 1, 2017	$	—	$	—	$	—
Total gains and losses included in earnings for the period⁽¹⁾
Gain on conversion of loans and accrued interest	2,671		—		2,671
Gain on exercise of Primary Warrant	—		4,616		4,616
Change in fair value of investment, net	115,381		30,900		146,281
Purchases, issues, sales and settlements
Purchases and issues	54,202		1,026		55,228
Total recurring fair value measurements⁽¹⁾	$	172,254	$	36,542	$	208,796

Marketable Securities [Table Text Block]

Short-term marketable securities for the periods presented were comprised of the following (in thousands):



			Gross Unrealized
Security Type	Cost		Gains		Losses		Fair Value
September 30, 2017:
U.S. government fixed income securities	$	57,427	$	60	$	—	$	57,487

December 31, 2016:
U.S. government fixed income securities	$	19,403	$	40	$	—	$	19,443