Financing Receivables: (Details) (USD $) In Millions, unless otherwise specified					9 Months Ended				9 Months Ended				9 Months Ended				9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Net investment in sales-type and direct financing leases	Dec. 31, 2011 Net investment in sales-type and direct financing leases	Sep. 30, 2012 Net investment in sales-type and direct financing leases Financing receivable, lower range of payment terms	Sep. 30, 2012 Net investment in sales-type and direct financing leases Financing receivable, upper range of payment terms	Sep. 30, 2012 Commercial financing receivables	Dec. 31, 2011 Commercial financing receivables	Sep. 30, 2012 Commercial financing receivables Financing receivable, lower range of payment terms	Sep. 30, 2012 Commercial financing receivables Financing receivable, upper range of payment terms	Sep. 30, 2012 Client loan receivables	Dec. 31, 2011 Client loan receivables	Sep. 30, 2012 Client loan receivables Financing receivable, lower range of payment terms	Sep. 30, 2012 Client loan receivables Financing receivable, upper range of payment terms	Sep. 30, 2012 Installment payment receivables	Dec. 31, 2011 Installment payment receivables	Sep. 30, 2012 Installment payment receivables Financing receivable, lower range of payment terms	Sep. 30, 2012 Installment payment receivables Financing receivable, upper range of payment terms
Financing receivables, current
Financing receivables, net, current	$ 14,925	$ 16,901	$ 3,887	$ 3,765			$ 5,417	$ 7,095			$ 4,750	$ 5,195			$ 871	$ 846
Financing receivables, noncurrent
Financing receivables, net, noncurrent	10,791	10,776	5,091	5,406			6	34			5,223	4,925			470	410
Financing receivables
Financing receivable, payment terms					2 years	6 years			30 days	90 days			1 year	7 years			1 year	3 years
Sales-type and direct financing leases, unguaranteed residual value			716	745
Sales-type and direct financing leases, unearned income			661	733
Allowance for credit losses			118	118			39	53			151	126			34	51
Financing receivables used as collateral for non-recourse borrowings	$ 668	$ 410