5)	Investments

The fair value of investments classified as short-term consists of the following:


	Years Ended December 31,
Available-for-sale investments:	2015		2014
Time deposits and certificates of deposit	$	11,892	$	20,948
Bankers acceptance drafts		728		82
Asset-backed securities		124,997		75,674
Corporate obligations		165,109		88,689
Municipal bonds		8,355		3,353
U.S. agency obligations		119,582		98,049

	$	430,663	$	286,795

The following table shows the gross unrealized gains and (losses) aggregated by investment category for available-for-sale investments:


As of December 31, 2015:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Short-term investments:
Available-for-sale investments:
Time deposits and certificates of deposit	$	11,893	$	—	$	(1	)	$	11,892
Bankers acceptance drafts		728		—		—			728
Asset-backed securities		125,271		—		(274	)		124,997
Corporate obligations		165,445		5		(341	)		165,109
Municipal bonds		8,346		13		(4	)		8,355
U.S. agency obligations		119,699		3		(120	)		119,582

	$	431,382	$	21	$	(740	)	$	430,663


As of December 31, 2014:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Short-term investments:
Available-for-sale investments:
Time deposits and certificates of deposit	$	20,949	$	—	$	(1	)	$	20,948
Bankers acceptance drafts		82		—		—			82
Asset-backed securities		75,778		5		(109	)		75,674
Corporate obligations		88,871		3		(185	)		88,689
Municipal bonds		3,357		—		(4	)		3,353
U.S. agency obligations		98,051		16		(18	)		98,049

	$	287,088	$	24	$	(317	)	$	286,795

The table above, which shows the gross unrealized gains and (losses) aggregated by investment category for available-for-sale investments as of December 31, 2014, reflects the inclusion of investments with contractual maturities greater than one year from the date of purchase within short-term investments.

Management has the ability, if necessary, to liquidate any of its investments in order to meet the Company’s liquidity needs in the next 12 months. Accordingly, those investments with contractual maturities greater than one year from the date of purchase are classified as short-term on the accompanying balance sheets.

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 and realized gains or losses are reflected in income and was not material in 2015, 2014 and 2013.