3)	Investments

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


	September 30, 2017		December 31, 2016
Available-for-sale investments:
Time deposits and certificates of deposit	$	21,503	$	23,818
Bankers’ acceptance drafts		3,452		1,439
Asset-backed securities		39,702		36,809
Commercial paper		21,215		24,381
Corporate obligations		80,099		46,707
Municipal bonds		45		591
Promissory note		1,075		675
U.S. treasury obligations		25,777		25,414
U.S. agency obligations		35,763		29,629

	$	228,631	$	189,463

Investments classified as long-term consists of the following:


	September 30, 2017		December 31, 2016
Available-for-sale investments:
Group insurance contracts	$	6,193	$	5,558
Cost method investments:
Minority interest in a private company⁽¹⁾		4,400		4,300

	$	10,593	$	9,858

⁽¹⁾	In April 2016, the Company invested $9,300 for a minority interest in a private company. For the year ended December 31, 2016, the Company recognized $5,000 of impairment charges related to this cost method investment. In July 2017, the Company invested an additional $100 in this private company.

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


	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
As of September 30, 2017:
Short-term investments:
Available-for-sale investments:
Time deposits and certificates of deposit	$	21,501	$	2	$	—		$	21,503
Bankers’ acceptance drafts		3,452		—		—			3,452
Asset-backed securities		39,709		17		(24	)		39,702
Commercial paper		21,278		—		(63	)		21,215
Corporate obligations		80,020		87		(8	)		80,099
Municipal bonds		45		—		—			45
Promissory note		1,075		—		—			1,075
U.S. treasury obligations		25,756		21		—			25,777
U.S. agency obligations		35,756		10		(3	)		35,763

	$	228,592	$	137	$	(98	)	$	228,631


	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
As of September 30, 2017:
Long-term investments:
Available-for-sale investments:
Group insurance contracts	$	6,193	$	—	$	—		$	6,193


	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
As of December 31, 2016:
Short-term investments:
Available-for-sale investments:
Time deposits and certificates of deposit	$	23,818	$	—	$	—		$	23,818
Bankers acceptance drafts		1,439		—		—			1,439
Asset-backed securities		36,847		6		(44	)		36,809
Commercial paper		24,423		—		(42	)		24,381
Corporate obligations		46,700		21		(14	)		46,707
Municipal bonds		591		—		—			591
Promissory note		675		—		—			675
U.S. treasury obligations		25,414		—		—			25,414
U.S. agency obligations		29,631		8		(10	)		29,629

	$	189,538	$	35	$	(110	)	$	189,463


	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
As of December 31, 2016:
Long-term investments:
Available-for-sale investments:
Group insurance contracts	$	6,276	$	—	$	(718	)	$	5,558

The tables above, which show the gross unrealized gains and (losses) aggregated by investment category for available-for-sale investments as of September 30, 2017 and December 31, 2016, 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 on the accompanying balance sheets.

The Company reviews and evaluates its investments for any indication of possible impairment. Based on this review, the Company has determined that the unrealized losses related to these investments at September 30, 2017 and December 31, 2017, were temporary.

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, 2017 and 2016.