Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Measurements [Abstract]

Fair Value Measurements

	As of December 31, 2011 Fair Value Measurements at the Reporting Date Using									As of December 31, 2012 Fair Value Measurements at the Reporting Date Using
		Quoted prices in active markets for identical instruments (level 1)		Significant other observable inputs (level 2)		Significant unobservable inputs (level 3)		Total balance		Quoted prices in active markets for identical instruments (level 1)		Significant other observable inputs (level 2)		Significant unobservable inputs (level 3)		Total balance
Cash equivalents-term deposits	$	256,555	$	-	$	-	$	256,555	$	153,805	$	-	$	-	$	153,805
Trading securities	$	231	$	-	$	-	$	231	$	179	$	-	$	-	$	179
Total	$	256,786	$	-	$	-	$	256,786	$	153,984	$	-	$	-	$	153,984