Short-term Investments (Tables)

12 Months Ended

Dec. 31, 2014

Short-term Investments [Abstract]

Short-term Investments

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

	December 31, 2014
Security Type	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. government fixed income securities	$	58,819	$	2	$	(263	)	$	58,558
Total short-term investments	$	58,819	$	2	$	(263	)	$	58,558

	December 31, 2013
Security Type	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. government fixed income securities	$	130,971	$	21	$	(975	)	$	130,017
Total short-term investments	$	130,971	$	21	$	(975	)	$	130,017