Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Measurements [Abstract]

Financial Assets And Liabilities That Were Recorded At Fair Value On A Recurring Basis [Table Text Block]

Recurring Fair Value Measurements	As of December 31, 2012
	Level 1	Level 2	Level 3	Total
ASSETS:
Cash equivalents	$       11,933	$            —	$          —	$       11,933
U.S. treasury securities held to maturity	$       41,978	$            —	$          —	$       41,978
Recurring Fair Value Measurements	As of December 31, 2011
	Level 1	Level 2	Level 3	Total
ASSETS:
Cash equivalents	$     77,004	$           —	$            —	$       77,004