Fair Value Measurement (Additional Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Mar. 31, 2012	Jun. 30, 2012 Level 3 [Member]	Mar. 31, 2012 Level 3 [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Long-lived assets carrying amount			$ 10
Long-lived assets fair value amount			7
Asset write-offs	$ 53	$ 3