Financial Instruments: (Details 4) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Foreign exchange forward contracts | Net Unrealized Gains/(Losses) on Cash Flow Hedges
Derivative Instruments, Gain (Loss)
Net gains (losses) before taxes in other comprehensive income/(loss), cash flow hedges of borrowings	$ 109,000,000	$ (138,000,000)
Interest rate swaps | Net Unrealized Gains/(Losses) on Cash Flow Hedges
Derivative Instruments, Gain (Loss)
Net gains (losses) before taxes in other comprehensive income/(loss), cash flow hedges of borrowings	1,000,000	1,000,000
Derivative instruments in fair value hedging relationships | Interest rate swaps
Derivative Instruments, Gain (Loss)
Notional amount	3,000,000,000	4,300,000,000
Average remaining maturity	6 years 7 months 6 days	5 years 1 month 6 days
Derivative instruments in cash flow hedging relationships | Foreign exchange forward contracts
Derivative Instruments, Gain (Loss)
Notional amount	10,800,000,000	10,700,000,000
Average remaining maturity	8 months 12 days	8 months 12 days
Gains (losses) expected to be reclassified to net income within the next 12 months	205,000,000	(79,000,000)
Maximum length of time hedged	4 years
Derivative instruments in cash flow hedging relationships | Interest rate swaps
Derivative Instruments, Gain (Loss)
Gains (losses) expected to be reclassified to net income within the next 12 months	1,000,000	1,000,000
Derivative instruments in net investment hedging relationships
Derivative Instruments, Gain (Loss)
Notional amount	4,600,000,000	3,300,000,000
Average remaining maturity	3 months 18 days	4 months 24 days
Derivative instruments not designated as hedging instruments | Foreign exchange forward and swap contracts
Derivative Instruments, Gain (Loss)
Notional amount	13,400,000,000	12,900,000,000
Maximum length of time hedged	1 year
Derivative instruments not designated as hedging instruments | Equity contracts
Derivative Instruments, Gain (Loss)
Notional amount	$ 1,200,000,000	$ 1,200,000,000