Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2013

Investments, Debt and Equity Securities [Abstract]

Summary of Marketable Securities

	September 30, 2013						December 31, 2012
	Cost		Unrealized Gain (Loss)		Fair Value		Cost		Unrealized Gain (Loss)		Fair Value
U.S. government securities	$	27	$	—	$	27	$	7	$	—	$	7
Corporate securities	30				30		11				11
Certificates of deposit	17				17		16				16
Other	31				31		25		1		26
Total marketable securities	$	105	$	—	$	105	$	59	$	1	$	60