Segments: (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenue:
Revenue	$ 25,783	[1]	$ 26,666	$ 50,456	$ 51,273
Total reportable segment
Revenue:
Revenue	27,529		28,558	53,991	55,052
Elimination of internal transactions
Revenue:
Revenue	(1,921)		(2,082)	(3,872)	(4,160)
Other revenue adjustments
Revenue:
Revenue	$ 175		$ 191	$ 336	$ 381

[1] Amounts may not add due to rounding.