Financing Receivables: (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Major Markets	Dec. 31, 2011 Major Markets	Mar. 31, 2012 Growth Markets	Dec. 31, 2011 Growth Markets	Mar. 31, 2012 Lease receivables	Dec. 31, 2011 Lease receivables	Dec. 31, 2010 Lease receivables	Mar. 31, 2012 Lease receivables Major Markets	Dec. 31, 2011 Lease receivables Major Markets	Dec. 31, 2010 Lease receivables Major Markets	Mar. 31, 2012 Lease receivables Growth Markets	Dec. 31, 2011 Lease receivables Growth Markets	Dec. 31, 2010 Lease receivables Growth Markets	Mar. 31, 2012 Client loan receivables	Dec. 31, 2011 Client loan receivables	Dec. 31, 2010 Client loan receivables	Mar. 31, 2012 Client loan receivables Major Markets	Dec. 31, 2011 Client loan receivables Major Markets	Dec. 31, 2010 Client loan receivables Major Markets	Mar. 31, 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	$ 19,730	$ 20,060	$ 15,055	$ 15,587	$ 4,675	$ 4,472	$ 8,396	$ 8,430		$ 6,446	$ 6,510		$ 1,949	$ 1,921		$ 11,335	$ 11,629		$ 8,609	$ 9,077		$ 2,726	$ 2,552
Collectively evaluated for impairment	19,465	19,692	14,901	15,321	4,564	4,370
Individually evaluated for impairment	266	368	155	266	111	102
Allowance for Credit Losses
Allowance for credit losses, beginning balance	307	353	203	234	104	119	117	118	126	74	79	84	43	40	42	194	189	226	128	125	150	66	64	76
Write-offs	(2)	(84)	(2)	(68)	0	(16)
Provision	3	44	(2)	39	5	5
Other	3	(5)	2	(1)	1	(4)
Allowance for credit losses, ending balance	311	307	202	203	109	104	117	118	126	74	79	84	43	40	42	194	189	226	128	125	150	66	64	76
Collectively evaluated for impairment	109	96	92	82	18	15
Individually evaluated for impairment	$ 202	$ 211	$ 110	$ 122	$ 91	$ 89