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

3 Months Ended

Mar. 31, 2015

Fair Value Disclosures [Abstract]

Investments

Details of our investments are as follows:

	March 31, 2015						December 31, 2014
	Cash and Cash		Short-Term		Long-Term		Cash and Cash		Short-Term		Long-Term
	Equivalents		Investments		Investments		Equivalents		Investments		Investments
Measured at fair value:
Available-for-sale securities:
Money market funds	$	442	$	—	$	—	$	522	$	—	$	—
Corporate obligations		160		365		—		97		390		—
U.S. Government agency and Treasury securities		390		1,697		—		365		1,952		—
Trading securities:
Mutual funds		—		—		193		—		—		185
Total		992		2,062		193		984		2,342		185
Other measurement basis:
Equity-method investments		—		—		27		—		—		27
Cost-method investments		—		—		12		—		—		12
Cash on hand		250		—		—		215		—		—
Total	$	1,242	$	2,062	$	232	$	1,199	$	2,342	$	224

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 as of March 31, 2015:

Due	Fair Value
One year or less	$	2,919
One to two years		135

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, 2015, and December 31, 2014. 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,
	2015		Level 1		Level 2
Assets:
Money market funds	$	442	$	442	$	—
Corporate obligations		525		—		525
U.S. Government agency and Treasury securities		2,087		1,632		455
Mutual funds		193		193		—
Total assets	$	3,247	$	2,267	$	980
Liabilities:
Deferred compensation	$	203	$	203	$	—
Total liabilities	$	203	$	203	$	—

	Fair Value
	December 31,
	2014		Level 1		Level 2
Assets:
Money market funds	$	522	$	522	$	—
Corporate obligations		487		—		487
U.S. Government agency and Treasury securities		2,317		1,762		555
Mutual funds		185		185		—
Total assets	$	3,511	$	2,469	$	1,042
Liabilities:
Deferred compensation	$	202	$	202	$	—
Total liabilities	$	202	$	202	$	—