4)	Investments

Investments classified as short-term consists of the following:


	June 30, 2016		December 31, 2015
Available-for-sale investments:
Time deposits and certificates of deposit	$	17,358	$	11,892
Bankers’ acceptance drafts		3,056		728
Asset-backed securities		14,173		124,997
Corporate obligations		19,468		165,109
Municipal bonds		595		8,355
U.S. treasury obligations		1,154		—
U.S. agency obligations		15,569		119,582

	$	71,373	$	430,663

Investments classified as long-term consists of the following:


	June 30, 2016		December 31, 2015
Available-for-sale investments:
Group insurance contracts		5,930		—

Cost method investments:
Minority interest in Reno Sub-Systems, Inc.	$	9,300	$	—

	$	15,230	$	—

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


As of June 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	$	17,358	$	—	$	—		$	17,358
Bankers’ acceptance drafts		3,056		—		—			3,056
Asset-backed securities		14,164		16		(7	)		14,173
Corporate obligations		19,454		21		(7	)		19,468
Municipal bonds		592		3		—			595
U.S. treasury obligations		1,151		3		—			1,154
U.S. agency obligations		15,563		6		—			15,569

	$	71,338	$	49	$	(14	)	$	71,373


As of June 30, 2016:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Long-term investments:
Available-for-sale investments:
Group insurance contracts	$	5,938	$	—	$	(8	)	$	5,930


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 June 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 six months ended June 30, 2016 and 2015.