Short-term Investments (Tables)

12 Months Ended

Dec. 31, 2017

Short-term Investments [Abstract]

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 year ended December 31, 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	33,922		8,317		42,239
Purchases, issues, sales and settlements
Purchases and issues(2)	54,202		1,026		55,228
Total recurring fair value measurements(1)	$	90,795	$	13,959	$	104,754

Short-term Investments

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

	December 31, 2016
Security Type	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. government fixed income securities	$	19,403	$	40	$	—	$	19,443