Long-Lived Assets by Geographic Area (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Long-lived assets:
Long-lived assets	$ 20,285	$ 19,816
United States
Long-lived assets:
Long-lived assets	16,016	15,963
International
Long-lived assets:
Long-lived assets	$ 4,269	$ 3,853