Financing Receivables: (Details) (USD $) In Millions, unless otherwise specified					3 Months Ended				3 Months Ended				3 Months Ended				3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Net investment in sales-type and direct financing leases	Dec. 31, 2012 Net investment in sales-type and direct financing leases	Mar. 31, 2013 Net investment in sales-type and direct financing leases Financing receivable, lower range of payment terms	Mar. 31, 2013 Net investment in sales-type and direct financing leases Financing receivable, upper range of payment terms	Mar. 31, 2013 Commercial financing receivables	Dec. 31, 2012 Commercial financing receivables	Mar. 31, 2013 Commercial financing receivables Financing receivable, lower range of payment terms	Mar. 31, 2013 Commercial financing receivables Financing receivable, upper range of payment terms	Mar. 31, 2013 Client loan receivables	Dec. 31, 2012 Client loan receivables	Mar. 31, 2013 Client loan receivables Financing receivable, lower range of payment terms	Mar. 31, 2013 Client loan receivables Financing receivable, upper range of payment terms	Mar. 31, 2013 Installment payment receivables	Dec. 31, 2012 Installment payment receivables	Mar. 31, 2013 Installment payment receivables Financing receivable, lower range of payment terms	Mar. 31, 2013 Installment payment receivables Financing receivable, upper range of payment terms
Financing receivables, current
Financing receivables, net, current	$ 16,141	$ 18,038	$ 3,960	$ 3,862			$ 6,025	$ 7,750			$ 5,113	$ 5,395			$ 1,044	$ 1,031
Financing receivables, noncurrent
Financing receivables, net, noncurrent	11,946	12,812	5,732	6,107			1	5			5,582	5,966			631	733
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			750	794
Sales-type and direct financing leases, unearned income			738	728
Allowance for credit losses			112	114			31	46			158	155			35	39
Financing receivables used as collateral for non-recourse borrowings	550	650
Financing receivables held for sale	$ 0	$ 0