Short-Term Investments (Tables)

9 Months Ended

Sep. 30, 2012

Short-Term Investments [Abstract]

Available-for-sale securities recorded at fair value with unrealized gains or losses

	September 30, 2012							December 31, 2011
			Amortized		Gross unrealized					Amortized		Gross unrealized
	Fair value		cost basis		gain(loss)			Fair value		cost basis		gain(loss)
Corporate notes, bonds and paper	$	13,414	$	13,409	$	5		$	31,180	$	31,217	$	(37	)
Government securities		3,558		3,559		(1	)		7,317		7,321		(4	)
Total	$	16,972	$	16,968	$	4		$	38,497	$	38,538	$	(41	)