Financing Receivables: (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Major Markets	Dec. 31, 2011 Major Markets	Sep. 30, 2012 Growth Markets	Dec. 31, 2011 Growth Markets	Sep. 30, 2012 Lease receivables	Dec. 31, 2011 Lease receivables	Dec. 31, 2010 Lease receivables	Sep. 30, 2012 Lease receivables Major Markets	Dec. 31, 2011 Lease receivables Major Markets	Dec. 31, 2010 Lease receivables Major Markets	Sep. 30, 2012 Lease receivables Growth Markets	Dec. 31, 2011 Lease receivables Growth Markets	Dec. 31, 2010 Lease receivables Growth Markets	Sep. 30, 2012 Client loan receivables	Dec. 31, 2011 Client loan receivables	Dec. 31, 2010 Client loan receivables	Sep. 30, 2012 Client loan receivables Major Markets	Dec. 31, 2011 Client loan receivables Major Markets	Dec. 31, 2010 Client loan receivables Major Markets	Sep. 30, 2012 Client loan receivables Growth Markets	Dec. 31, 2011 Client loan receivables Growth Markets	Dec. 31, 2010 Client loan receivables Growth Markets
Financing Receivables:
Ending Balance	$ 19,790	$ 20,060	$ 14,771	$ 15,587	$ 5,019	$ 4,472	$ 8,273	$ 8,430		$ 6,353	$ 6,510		$ 1,920	$ 1,921		$ 11,518	$ 11,629		$ 8,419	$ 9,077		$ 3,099	$ 2,552
Collectively evaluated for impairment	19,539	19,692	14,628	15,321	4,911	4,370
Individually evaluated for impairment	251	368	143	266	108	102
Allowance for Credit Losses
Allowance for credit losses, beginning balance	307	353	203	234	104	119	118	118	126	70	79	84	48	40	42	196	189	226	124	125	150	72	64	76
Write-offs	(9)	(84)	(8)	(68)	(1)	(16)
Provision	18	44	0	39	18	5
Other	(2)	(5)	(1)	(1)	(1)	(4)
Allowance for credit losses, ending balance	314	307	194	203	120	104	118	118	126	70	79	84	48	40	42	196	189	226	124	125	150	72	64	76
Collectively evaluated for impairment	104	96	82	82	22	15
Individually evaluated for impairment	$ 210	$ 211	$ 112	$ 122	$ 98	$ 89