Investments

At December 31, 2012 and 2011, the estimated fair value of our short-term and long-term investments classified as available for sale, are as follows:



	December 31, 2012
	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In millions)
Short-term investments:
Restricted cash	$	15	$	—	$	—	$	15
Corporate debt securities	1,150		3		—		1,153
Government and agency securities	20		—		—		20
Time deposits and other	765		—		—		765
Equity instruments	8		630		—		638
	$	1,958	$	633	$	—	$	2,591
Long-term investments:
Corporate debt securities	2,615		54		—		2,669
Government and agency securities	41		1		—		42
	$	2,656	$	55	$	—	$	2,711



	December 31, 2011
	Gross Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(In millions)
Short-term investments:
Restricted cash	$	19	$	—	$	—		$	19
Corporate debt securities	448		1		—			449
Government and agency securities	42		—		—			42
Time deposits and other	82		—		—			82
Equity instruments	8		638		—			646
	$	599	$	639	$	—		$	1,238
Long-term investments:
Restricted cash	$	1	$	—	$	—		$	1
Corporate debt securities	2,238		6		(58		)	2,186
Government and agency securities	70		1		—			71
	$	2,309	$	7	$	(58	)	$	2,258

At December 31, 2012 and 2011, we held $6 million and $5 million, respectively, of time deposits classified as held to maturity which are recorded at amortized cost.

We had no material long-term or short-term investments that have been in a continuous unrealized loss position for greater than 12 months as of December 31, 2012. Amounts reclassified to earnings from unrealized gains and losses were not material in 2012, 2011 and 2010,

Our fixed-income investment portfolio consists of corporate debt securities and government and agency securities that have a maximum maturity of six years. The corporate debt and government and agency securities that we invest in are generally deemed to be low risk based on their credit ratings from the major rating agencies. The longer the duration of these securities, the more susceptible they are to changes in market interest rates and bond yields. As interest rates increase, those securities purchased at a lower yield show a mark-to-market unrealized loss. The unrealized losses are due primarily to changes in credit spreads and interest rates. We expect to realize the full value of all these investments upon maturity or sale. As of December 31, 2012, these securities had a weighted average remaining duration of approximately 18 months. Restricted cash is held primarily in money market funds and interest bearing accounts for letters of credit related primarily to our global sabbatical program and various lease arrangements.

The estimated fair values of our short-term and long-term investments classified as available for sale by date of contractual maturity at December 31, 2012 are as follows:



	December 31, 2012
	(In millions)
One year or less (including restricted cash of $15)	$	2,591
One year through two years	1,016
Two years through three years	493
Three years through four years	766
Four years through five years	420
Five years through six years	16
	$	5,302

Equity and cost method investments

We have made multiple equity and cost method investments which are reported in long-term investments on our consolidated balance sheet. As of December 31, 2012 and 2011, our equity and cost method investments totaled $327 million and $190 million, respectively. During 2012, we entered into a joint venture arrangement with a third party resulting in an equity investment of $130 million in exchange for our contribution of $12 million cash and commitment to contribute certain assets of a business unit upon obtaining further regulatory approvals.