Note 3. Investments

The following tables summarize the Company’s investments (in thousands):

 

		July 30, 2016
						Gross				Gross
		Amortized				Unrealized				Unrealized				Estimated
		Cost				Gains				Losses				Fair Value
Short-term investments:
Available-for-sale:
Corporate debt securities		$	475,483			$	3,519			$	(154	)		$	478,848
U.S. government and agency debt			206,056				273				(53	)			206,276
Asset backed securities			51,489				132				(13	)			51,608
Foreign government and agency debt			14,603				14				(2	)			14,615
Municipal debt securities			28,873				41				(4	)			28,910
Held-to-maturity:
Time deposits			125,000				—				—				125,000
Total short-term investments			901,504				3,979				(226	)			905,257
Long-term investments:
Available-for-sale:
Auction rate securities			8,974				—				—				8,974
Total long-term investments			8,974				—				—				8,974
Total investments		$	910,478			$	3,979			$	(226	)		$	914,231

 

		January 30, 2016
						Gross				Gross
		Amortized				Unrealized				Unrealized				Estimated
		Cost				Gains				Losses				Fair Value
Short-term investments:
Available-for-sale:
Corporate debt securities		$	558,337			$	766			$	(1,282	)		$	557,821
U.S. government and agency debt			317,595				64				(254	)			317,405
Asset backed securities			76,711				81				(56	)			76,736
Foreign government and agency debt			21,370				2				(14	)			21,358
Municipal debt securities			31,211				45				(7	)			31,249
Total short-term investments			1,005,224				958				(1,613	)			1,004,569
Long-term investments:
Available-for-sale:
Auction rate securities			11,296				—				—				11,296
Total long-term investments			11,296				—				—				11,296
Total investments		$	1,016,520			$	958			$	(1,613	)		$	1,015,865

As of July 30, 2016, the Company’s investment portfolio included auction rate securities with an aggregate par value of $10.0 million. Although these auction rate securities have continued to pay interest and the underlying collateral has not deteriorated, there is currently limited trading volume. The Company uses a discounted cash flow model to estimate the fair value of the auction rate securities based on its estimated timing and amount of future interest and principal payments. In developing the cash flow model, the Company considers the credit quality and liquidity of the underlying securities and related issuer, the collateralization of underlying security investments and other considerations.

The Company made a determination in January 2016 that it did not expect to recover the par value of these auction rate securities and considers any impairment of these securities to be other-than-temporary. There has been no change in circumstances since January 2016 based upon the current time horizon for holding these securities and the continuation of an illiquid market. Based on the Company’s assessment of fair value as of July 30, 2016, the Company determined there was no further impairment of these auction rate securities.

In the six months ended July 30, 2016, the Company sold auction rate securities with an aggregate par value of $2.5 million for total net proceeds of $2.4 million. The carrying value of these auction rate securities was $2.3 million and resulted in a net gain of $0.1 million in the six months ended July 30, 2016.

Gross realized gains and gross realized losses on sales of available-for-sale securities are presented in the following tables (in thousands):

 

		Three Months Ended								Six Months Ended
		July 30,				August 1,				July 30,				August 1,
		2016				2015				2016				2015
Gross realized gains		$	280			$	255			$	668			$	698
Gross realized losses			(19	)			(230	)			(243	)			(337	)
Total net realized gains		$	261			$	25			$	425			$	361

 

The contractual maturities of available-for-sale securities are presented in the following tables (in thousands):

 

		July 30, 2016								January 30, 2016
		Amortized				Estimated				Amortized				Estimated
		Cost				Fair Value				Cost				Fair Value
Due in one year or less		$	355,835			$	355,931			$	304,117			$	304,035
Due between one and five years			538,247				541,894				689,847				689,279
Due over five years			16,396				16,406				22,556				22,551
		$	910,478			$	914,231			$	1,016,520			$	1,015,865

For individual securities that have been in a continuous unrealized loss position, the fair value and gross unrealized loss for these securities aggregated by investment category and length of time in an unrealized position are presented in the following tables (in thousands):

 

		July 30, 2016
		Less than 12 months								12 months or more								Total
		Fair				Unrealized				Fair				Unrealized				Fair				Unrealized
		Value				Loss				Value				Loss				Value				Loss
Corporate debt securities		$	57,734			$	(75	)		$	20,946			$	(79	)		$	78,680			$	(154	)
U.S. government and agency debt			60,760				(46	)			6,993				(7	)			67,753				(53	)
Asset backed securities			7,003				(6	)			3,994				(7	)			10,997				(13	)
Foreign government and agency debt			4,411				(2	)			—				—				4,411				(2	)
Municipal debt securities			1,296				(1	)			1,497				(3	)			2,793				(4	)
Total securities		$	131,204			$	(130	)		$	33,430			$	(96	)		$	164,634			$	(226	)
		January 30, 2016
		Less than 12 months								12 months or more								Total
		Fair				Unrealized				Fair				Unrealized				Fair				Unrealized
		Value				Loss				Value				Loss				Value				Loss
Corporate debt securities		$	283,138			$	(1,237	)		$	14,383			$	(45	)		$	297,521			$	(1,282	)
U.S. government and agency debt			263,325				(254	)			—				—				263,325				(254	)
Asset backed securities			46,646				(56	)			—				—				46,646				(56	)
Foreign government and agency debt			16,458				(14	)			—				—				16,458				(14	)
Municipal debt securities			2,943				(5	)			1,571				(2	)			4,514				(7	)
Total securities		$	612,510			$	(1,566	)		$	15,954			$	(47	)		$	628,464			$	(1,613	)