Commitments: (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Extended lines of credit	Dec. 31, 2012 Extended lines of credit	Sep. 30, 2013 Financing for client purchase agreements	Dec. 31, 2012 Financing for client purchase agreements	Sep. 30, 2013 Financial guarantees	Dec. 31, 2012 Financial guarantees
Other Commitments [Line Items]
Unused amounts in lines of credit to third-party entities and commitments for future financing to clients			$ 5,359	$ 4,719	$ 1,692	$ 1,513
Guarantor obligations, maximum exposure							52	65
Movement in standard warranty liability
Beginning Balance	394	407
Current period accruals	238	270
Accrual adjustments to reflect actual experience	21	(18)
Charges incurred	(292)	(295)
Ending Balance	$ 362	$ 364