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, 2013	Dec. 31, 2012	Mar. 31, 2013 Major Markets	Dec. 31, 2012 Major Markets	Mar. 31, 2013 Growth Markets	Dec. 31, 2012 Growth Markets	Mar. 31, 2013 Lease receivables	Dec. 31, 2012 Lease receivables	Dec. 31, 2011 Lease receivables	Mar. 31, 2013 Lease receivables Major Markets	Dec. 31, 2012 Lease receivables Major Markets	Dec. 31, 2011 Lease receivables Major Markets	Mar. 31, 2013 Lease receivables Growth Markets	Dec. 31, 2012 Lease receivables Growth Markets	Dec. 31, 2011 Lease receivables Growth Markets	Mar. 31, 2013 Client loan receivables	Dec. 31, 2012 Client loan receivables	Dec. 31, 2011 Client loan receivables	Mar. 31, 2013 Client loan receivables Major Markets	Dec. 31, 2012 Client loan receivables Major Markets	Dec. 31, 2011 Client loan receivables Major Markets	Mar. 31, 2013 Client loan receivables Growth Markets	Dec. 31, 2012 Client loan receivables Growth Markets	Dec. 31, 2011 Client loan receivables Growth Markets
Financing Receivables
Ending Balance	$ 21,524	$ 22,510	$ 15,511	$ 16,701	$ 6,013	$ 5,808	$ 8,958	$ 9,174		$ 6,823	$ 7,036		$ 2,135	$ 2,138		$ 12,566	$ 13,336		$ 8,688	$ 9,666		$ 3,878	$ 3,670
Collectively evaluated for impairment	21,259	22,254	15,397	16,570	5,862	5,684
Individually evaluated for impairment	265	256	114	131	151	125
Allowance for Credit Losses
Allowance for credit losses, beginning balance	318	307	180	203	138	104	112	114	118	52	59	79	60	55	40	193	204	189	96	121	125	98	84	64
Write-offs	(18)	(15)	(16)	(14)	(2)	(1)
Provision	9	28	(13)	(9)	21	38
Other	(4)	(2)	(4)	0	0	(2)
Allowance for credit losses, ending balance	306	318	148	180	157	138	112	114	118	52	59	79	60	55	40	193	204	189	96	121	125	98	84	64
Collectively evaluated for impairment	85	98	56	69	29	29
Individually evaluated for impairment	$ 220	$ 220	$ 92	$ 111	$ 129	$ 109