Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2012

Marketable Securities [Abstract]

Schedule of marketable securities

	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair value
At December 31, 2012:
Certificates of deposit	$	6,500	$	—	$	(1	)	$	6,499
Treasury bills	14,996		1		—			14,997
	$	21,496	$	1	$	(1	)	$	21,496