3)	Investments

The fair value of short-term investments with maturities or estimated lives of less than one year consists of the following:


	June 30, 2015		December 31, 2014
Available-for-sale investments:
Time deposits and certificates of deposit	$	23,630	$	20,900
Asset-backed securities		155		—
Bankers’ acceptance drafts		222		82
Commercial paper		3,450		—
Corporate obligations		59,719		24,020
Municipal bonds		7,057		2,099
U.S. agency obligations		83,200		82,493

	$	177,433	$	129,594

The fair value of long-term investments with maturities of more than one year consists of the following:


	June 30, 2015		December 31, 2014
Available-for-sale investments:
Time deposits and certificates of deposit	$	—	$	48
Asset-backed securities		140,677		75,674
Corporate obligations		103,570		64,669
Municipal bonds		605		1,254
U.S. agency obligations		12,003		15,556

	$	256,855	$	157,201

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 June 30, 2015:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Short-term investments:
Time deposits and certificates of deposit	$	23,630	$	—	$	—		$	23,630
Asset-backed securities		256		—		(101	)		155
Bankers’ acceptance drafts		222		—		—			222
Commercial paper		3,449		1		—			3,450
Corporate obligations		59,735		7		(23	)		59,719
Municipal bonds		7,055		6		(4	)		7,057
U.S. agency obligations		83,176		25		(1	)		83,200

	$	177,523	$	39	$	(129	)	$	177,433

Long-term investments:
Asset-backed securities	$	140,695	$	50	$	(68	)	$	140,677
Corporate obligations		103,709		17		(156	)		103,570
Municipal bonds		615		—		(10	)		605
U.S. agency obligations		11,998		6		(1	)		12,003

	$	257,017	$	73	$	(235	)	$	256,855


As of December 31, 2014:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Short-term investments:
Time deposits and certificates of deposit	$	20,901	$	—	$	(1	)	$	20,900
Bankers’ acceptance drafts		82		—		—			82
Corporate obligations		24,029		2		(11	)		24,020
Municipal bonds		2,100		—		(1	)		2,099
U.S. agency obligations		82,488		14		(9	)		82,493

	$	129,600	$	16	$	(22	)	$	129,594

Long-term investments:
Time deposits and certificates of deposit	$	48	$	—	$	—		$	48
Asset-backed securities		75,778		5		(109	)		75,674
Corporate obligations		64,842		1		(174	)		64,669
Municipal bonds		1,258		—		(4	)		1,254
U.S. agency obligations		15,563		2		(9	)		15,556

	$	157,489	$	8	$	(296	)	$	157,201

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 immaterial for both the three and six months ended June 30, 2015 and 2014, respectively.

In accordance with the Company’s investment policy, no security shall have a maturity or average life longer than three years. The average duration of the portfolio shall be no more than one year. Corporate securities must have ratings of A3/A- or better. Asset-backed securities must be rated AAA. Short-term ratings of A-2/P2/F2 or higher are also permitted. With respect to compliance with these investment guidelines, the rating agencies include Moody’s Investor Service, Standard & Poor’s and Fitch Investor Service. The middle of Moody’s, Standard & Poor’s and Fitch rating shall be used to determine compliance with credit quality guidelines. If a security is rated by two rating agencies, the lower rating will apply. If only one rating exists, that rating shall be used.