Commitments: (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Extended lines of credit	Dec. 31, 2012 Extended lines of credit	Mar. 31, 2013 Financing for client purchase agreements	Dec. 31, 2012 Financing for client purchase agreements	Mar. 31, 2013 Financial guarantees	Dec. 31, 2012 Financial guarantees
Commitments, guarantees:
Unused amounts in lines of credit to third-party entities and commitments for future financing to clients			$ 5,213	$ 4,719	$ 1,734	$ 1,513
Guarantor obligations, maximum exposure							59	65
Movement in standard warranty liability
Beginning Balance	394	407
Current period accruals	71	88
Accrual adjustments to reflect actual experience	9	(3)
Charges incurred	(93)	(102)
Ending Balance	$ 381	$ 390