Available-for-sale investments (Tables)

6 Months Ended

Jun. 30, 2011

Available-for-sale investments [Abstract]

Amortized cost, gross unrealized gains, gross unrealized losses and estimated fair values of available-for-sale investments by type of security

			Gross		Gross			Estimated
	Amortized		unrealized		unrealized			fair
Type of security as of June 30, 2011	cost		gains		losses			value
U.S. Treasury securities	$	2,896	$	13	$	(2	)	$	2,907
Other government related debt securities:
Obligations of U.S. government agencies and FDIC guaranteed bank debt		1,537		22		—			1,559
Foreign and other		795		17		—			812
Corporate debt securities:
Financial		2,887		61		(4	)		2,944
Industrial		2,963		77		(4	)		3,036
Other		342		12		—			354
Mortgage and asset backed securities		1,541		7		(4	)		1,544
Money market mutual funds		5,677		—		—			5,677
Other short-term interest bearing securities		157		—		—			157
Total debt security investments		18,795		209		(14	)		18,990
Equity securities		52		—		(5	)		47
	$	18,847	$	209	$	(19	)	$	19,037

			Gross		Gross			Estimated
	Amortized		unrealized		unrealized			fair
Type of security as of December 31, 2010	cost		gains		losses			value
U.S. Treasury securities	$	5,044	$	50	$	(14	)	$	5,080
Other government related debt securities:
Obligations of U.S. government agencies and FDIC guaranteed bank debt		2,158		51		(1	)		2,208
Foreign and other		837		16		(1	)		852
Corporate debt securities:
Financial		2,252		53		(9	)		2,296
Industrial		2,441		71		(5	)		2,507
Other		307		10		(1	)		316
Mortgage and asset backed securities		841		5		(5	)		841
Money market mutual funds		3,030		—		—			3,030
Other short-term interest bearing securities		147		—		—			147
Total debt security investments		17,057		256		(36	)		17,277
Equity securities		50		—		(2	)		48
	$	17,107	$	256	$	(38	)	$	17,325

Fair values of available-for-sale investments by classification in the consolidated balance sheets

	June 30,		December 31,
Classification in the Condensed Consolidated Balance Sheets	2011		2010
Cash and cash equivalents	$	5,816	$	3,142
Marketable securities		13,174		14,135
Other assets — noncurrent		47		48
	$	19,037	$	17,325

Fair values of available-for-sale debt security investments by contractual maturity

	June 30,		December 31,
Contractual maturity	2011		2010
Maturing in one year or less	$	6,609	$	4,118
Maturing after one year through three years		6,138		6,736
Maturing after three years through five years		5,168		5,812
Maturing after five years		1,075		611
Total debt security investments	$	18,990	$	17,277