Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 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)	9/30/13		12/31/12		9/30/13			12/31/12			9/30/13		12/31/12		9/30/13			12/31/12
Cash equivalents	$	209	$	284	$	26		$	46		$	—	$	—	$	235		$	330
Marketable securities:
Corporate debt securities	—		—		88			82			—		—		88			82
U.S. government and agency debt securities	—		—		11			16			—		—		11			16
Non-U.S. government debt securities	—		—		—			1			—		—		—			1
Asset-backed debt securities	—		—		14			6			—		—		14			6
Certificates of deposit	—		—		17			16			—		—		17			16
Municipal debt securities	—		—		8			10			—		—		8			10
Derivative assets	—		—		3			3			—		—		3			3
Derivative liabilities	—		—		(3		)	(2		)	—		—		(3		)	(2		)