Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2013

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 June 30, 2013
	Level 1	Level 2	Level 3	Total
ASSETS:
Cash equivalents	$       8,947	$            —	$          —	$       8,947
U.S. Treasury securities held to maturity	$       44,990	$            —	$          —	$       44,990
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