Commitments: (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Extended lines of credit	Dec. 31, 2011 Extended lines of credit	Mar. 31, 2012 Financing for client purchase agreements	Dec. 31, 2011 Financing for client purchase agreements	Mar. 31, 2012 Financial guarantees	Dec. 31, 2011 Financial guarantees
Commitments, guarantees:
Unused amounts in lines of credit to third-party entities and commitments for future financing to clients			$ 4,247	$ 4,040	$ 2,731	$ 2,567
Guarantor obligations, maximum exposure							38	42
Movement in standard warranty liability
Beginning Balance	407	375
Current period accruals	88	93
Accrual adjustments to reflect actual experience	(3)	3
Charges incurred	(102)	(105)
Ending Balance	$ 390	$ 366