Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2013

Investments, Debt and Equity Securities [Abstract]

Summary of Marketable Securities

	March 31, 2013						December 31, 2012
	Cost		Unrealized Gains		Fair Value		Cost		Unrealized Gains		Fair Value
U.S. government securities	$	7	$	—	$	7	$	7	$	—	$	7
Corporate securities	11				11		11				11
Certificates of deposit	18				18		16				16
Other	25		2		27		25		1		26
Total marketable securities	$	61	$	2	$	63	$	59	$	1	$	60