Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2011

Intangible Assets [Abstract]

Intangible Assets with definite lives

	As of June 30, 2011							As of December 31, 2010
	Gross							Gross
	Carrying		Accumulated					Carrying		Accumulated
(millions)	Amount		Amortization			Net		Amount		Amortization			Net
Intangible Assets with Definite Lives:
Customer relationships	$	70	$	(30	)	$	40	$	70	$	(26	)	$	44
Other		9		(5	)		4		9		(5	)		4
Total	$	79	$	(35	)	$	44	$	79	$	(31	)	$	48

Estimated annual amortization expense intangible assets

(millions)	2011		2012		2013		2014		2015		2016
Estimated annual amortization expense	$	8	$	8	$	7	$	7	$	7	$	7

Intangible Assets with Indefinite Lives

	As of June 30, 2011						As of December 31, 2010
	Gross						Gross
	Carrying		Impairment				Carrying		Impairment
(millions)	Amount		Charges		Net		Amount		Charges			Net
Intangible Assets with Indefinite Lives:
Trade names	$	22	$	—	$	22	$	22	$	—		$	22
Other		8		—		8		9		(1	)		8
Total	$	30	$	—	$	30	$	31	$	(1	)	$	30