Valuation of debt and equity investments and certain liabilities (Tables)

3 Months Ended

Mar. 31, 2013

Valuation of debt and equity investments and certain liabilities [Abstract]

Investments

Details of our investments are as follows:

	March 31, 2013						December 31, 2012
	Cash and Cash Equivalents		Short-term Investments		Long-term Investments		Cash and Cash Equivalents		Short-term Investments		Long-term Investments
Measured at fair value:
Available-for-sale securities
Money market funds	$	208	$	—	$	—	$	211	$	—	$	—
Corporate obligations	200		308		—		188		325		—
U.S. Government agency and Treasury securities	827		2,161		—		795		2,224		—
Trading securities
Mutual funds	—		—		159		—		—		159
Total	$	1,235	$	2,469	$	159	$	1,194	$	2,549	$	159
Other measurement basis:
Equity-method investments	$	—	$	—	$	23	$	—	$	—	$	34
Cost-method investments	—		—		22		—		—		22
Cash on hand	158		—		—		222		—		—
Total	$	1,393	$	2,469	$	204	$	1,416	$	2,549	$	215

Aggregate Maturities of Investments in Debt Securities Classified as Available-for-sale

The following table presents the aggregate maturities of investments in debt securities classified as available for sale at March 31, 2013:

Due	Fair Value
One year or less	$	3,363
One to three years	341

Assets and Liabilities Accounted for at Fair Value

The following are our assets and liabilities that were accounted for at fair value on a recurring basis as of March 31, 2013, and December 31, 2012. For these periods, we had no level 3 assets or liabilities. These tables do not include cash on hand, assets held by our postretirement plans, or assets and liabilities that are measured at historical cost or any basis other than fair value.

	Fair Value
	March 31, 2013		Level 1		Level 2
Assets:
Money market funds	$	208	$	208	$	—
Corporate obligations	508		—		508
U.S. Government agency and Treasury securities	2,988		1,352		1,636
Mutual funds	159		159		—
Total assets	$	3,863	$	1,719	$	2,144
Liabilities:
Deferred compensation	177		177		—
Total liabilities	$	177	$	177	$	—

	Fair Value
	December 31, 2012		Level 1		Level 2
Assets:
Money market funds	$	211	$	211	$	—
Corporate obligations	513		—		513
U.S. Government agency and Treasury securities	3,019		1,145		1,874
Mutual funds	159		159		—
Total assets	$	3,902	$	1,515	$	2,387
Liabilities:
Deferred compensation	174		174		—
Total liabilities	$	174	$	174	$	—

Reconciliation of Change in Fair Value for Level 3 Assets

The following table summarizes the change in the fair values for Level 3 assets for the periods ended March 31, 2013 and 2012:  

	Level 3
Changes in fair value during the period (pre-tax):	Auction-rate Securities
Balance, December 31, 2011	$	134
Change in unrealized loss – included in AOCI	5
Redemptions	(1		)
Sales	(20		)
Balance, March 31, 2012	118
Change in unrealized loss – included in AOCI	8
Redemptions	(83		)
Sales	(43		)
Balance, December 31, 2012 and March 31, 2013	$	—