5)	Investments

Investments classified as short-term consists of the following:


	Years Ended December 31,
Available-for-sale investments:	2016		2015
Time deposits and certificates of deposit	$	23,818	$	11,892
Bankers’ acceptance drafts		1,439		728
Asset-backed securities		36,809		124,997
Commercial paper		24,381		—
Corporate obligations		46,707		165,109
Municipal bonds		591		8,355
Promissory note		675		—
U.S. treasury obligations		25,414		—
U.S. agency obligations		29,629		119,582

	$	189,463	$	430,663

Investments classified as long-term consists of the following:


	Years Ended December 31,
Available-for-sale investments:	2016		2015
Group insurance contracts	$	5,558	$	—
Cost method investments:
Minority interest in a private company(1)		4,300		—

	$	9,858	$	—

(1)	In April of 2016 the Company invested $9,300 for a minority interest in a private company. During 2016, the Company recognized $5,000 of impairment charges related to this cost method investment.

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


As of December 31, 2016:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
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


As of December 31, 2016:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Long-term investments:
Available-for-sale investments:
Group insurance contracts	$	6,276	$	—	$	(718	)	$	5,558
Cost method investments:
Minority interest in a private company(1)		4,300		—		—			4,300

	$	10,576	$	—	$	(718	)	$	9,858

(1)	In April of 2016 the Company invested $9,300 for a minority interest in a private company. During 2016, the Company recognized $5,000 of impairment charges related to this cost method investment.


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 December 31, 2016 and 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 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 2016, 2015 and 2014.