Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2013

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on a Recurring Basis

Our assets and liabilities measured at fair value on a recurring basis were as follows:

	Quoted Prices in Active Markets for Identical Assets (Level 1)				Significant Other Observable Inputs (Level 2)					Significant Unobservable Inputs (Level 3)				Total
(millions)	12/31/13		12/31/12		12/31/13		12/31/12			12/31/13		12/31/12		12/31/13		12/31/12
Cash equivalents	$	549	$	284	$	24	$	46		$	—	$	—	$	573	$	330
Marketable securities:
Corporate debt securities	—		—		87		82			—		—		87		82
U.S. government and agency debt securities	—		—		12		16			—		—		12		16
Non-U.S. government debt securities	—		—		—		1			—		—		—		1
Asset-backed debt securities	—		—		20		6			—		—		20		6
Certificates of deposit	—		—		17		16			—		—		17		16
Municipal debt securities	—		—		6		10			—		—		6		10
Derivative assets	—		—		5		3			—		—		5		3
Derivative liabilities	—		—		—		(2		)	—		—		—		(2		)