4)	Investments

Investments classified as short-term consists of the following:


	September 30, 2016		December 31, 2015
Available-for-sale investments:
Time deposits and certificates of deposit	$	1,395	$	11,892
Bankers’ acceptance drafts		2,487		728
Asset-backed securities		18,326		124,997
Commercial paper		2,793		—
Corporate obligations		16,701		165,109
Municipal bonds		593		8,355
U.S. treasury obligations		1,152		—
U.S. agency obligations		9,657		119,582

	$	53,104	$	430,663

Investments classified as long-term consists of the following:


	September 30, 2016		December 31, 2015
Available-for-sale investments:
Group insurance contracts	$	5,956	$	—
Cost method investments:
Minority interest in Reno Sub-Systems, Inc.		9,300		—

	$	15,256	$	—

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 September 30, 2016:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Short-term investments:
Available-for-sale investments:
Time deposits and certificates of deposit	$	1,395	$	—	$	—		$	1,395
Bankers’ acceptance drafts		2,487		—		—			2,487
Asset-backed securities		18,317		13		(4	)		18,326
Commercial paper		2,794		—		(1	)		2,793
Corporate obligations		16,699		15		(13	)		16,701
Municipal bonds		592		1		—			593
U.S. treasury obligations		1,151		1		—			1,152
U.S. agency obligations		9,653		4		—			9,657

	$	53,088	$	34	$	(18	)	$	53,104


As of September 30, 2016:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Long-term investments:
Available-for-sale investments:
Group insurance contracts	$	5,988	$	—	$	(32	)	$	5,956


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

The tables above, which show the gross unrealized gains and (losses) aggregated by investment category for available-for-sale investments as of September 30, 2016 and December 31, 2015, reflect the inclusion within short-term investments of investments with contractual maturities greater than one year from the date of purchase. 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 investments on the accompanying balance sheet.

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 and nine months ended September 30, 2016 and 2015.