Cash and Cash Equivalents and Investments (Tables)

6 Months Ended

Jun. 30, 2014

Cash and Cash Equivalents and Investments [Abstract]

Schedule of Cash, Cash Equivalents and Short-term Investments [Table Text Block]

	As of June 30, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash and cash equivalents	$	27,725	$	—	$	—		$	27,725
Securities maturing within one year:
Certificates of deposit	552		—		—			552
U.S. treasury securities	50,762		5		—			50,767
Total short-term investments	$	51,314	$	5	$	—		$	51,319
Total cash and cash equivalents and investments	$	79,039	$	5	$	—		$	79,044
	As of December 31, 2013
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
			(in thousands)
Cash and cash equivalents	$	37,499	$	—	$	—		$	37,499
Securities maturing within one year:
Certificates of deposit	552		—		—			552
U.S. treasury securities	91,075		3		(1		)	91,077
Total short-term investments	$	91,627	$	3	$	(1	)	$	91,629
Total cash and cash equivalents and investments	$	129,126	$	3	$	(1	)	$	129,128