Investments

The fair value of short-term investments with maturities or estimated lives of less than one year consists of the following:


	March 31, 2014		December 31, 2013
Available-for-sale investments:
Bankers’ acceptance drafts	$	637	$	491
Time deposits		3,442		3,439
Commercial paper and certificates of deposit		127,524		114,984
Corporate obligations		16,826		18,351
U.S. agency obligations		158,084		162,450

		306,513		299,715
Trading investments:
Mutual funds		—		1,000

	$	306,513	$	300,715

The fair value of long-term investments with maturities of more than one year consists of the following:


	March 31, 2014		December 31, 2013
Available-for-sale investments:
Time deposits	$	54	$	54
U.S. agency obligations		53,566		60,351

	$	53,620	$	60,405

The following tables show the gross unrealized gains and (losses) aggregated by investment category for short-term and long-term available-for-sale investments:


As of March 31, 2014:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Short-term investments:
Bankers’ acceptance drafts	$	637	$	—	$	—		$	637
Time deposits		3,442		—		—			3,442
Commercial paper and certificates of deposit		127,514		14		(4	)		127,524
Corporate obligations		16,827		1		(2	)		16,826
U.S. agency obligations		158,044		48		(8	)		158,084

	$	306,464	$	63	$	(14	)	$	306,513

Long-term investments:
Time deposits	$	54	$	—	$	—		$	54
U.S. agency obligations		53,558		18		(10	)		53,566

	$	53,612	$	18	$	(10	)	$	53,620


As of December 31, 2013:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Short-term investments:
Available-for-sale investments:
Time deposits	$	3,439	$	—	$	—		$	3,439
Bankers’ acceptance drafts		491		—		—			491
Commercial paper and certificates of deposit		114,973		15		(4	)		114,984
Corporate obligations		18,360		—		(9	)		18,351
U.S. agency obligations		162,430		22		(2	)		162,450

	$	299,693	$	37	$	(15	)	$	299,715

Long-term investments:
Time Deposits	$	54	$	—	$	—		$	54
U.S. agency obligations		60,374		9		(32	)		60,351

	$	60,428	$	9	$	(32	)	$	60,405

Interest income is accrued as earned. Dividend income is recognized as income on the date the stock trades “ex-dividend.” The cost of marketable securities sold is determined by the specific identification method. Realized gains or (losses) are reflected in income and were not material for the three months ended March 31, 2014 and 2013, respectively.

The gains and losses for trading investments were immaterial for the three months ended March 31, 2014 and 2013.