Financial Instruments: (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Financial Instruments:
Impairments of non-financial assets	$ 0	$ 0
Financial assets and financial liabilities measured at fair value on a recurring basis:
Debt securities - noncurrent	9		10
Available-for-sale equity investments	17		34
Derivative assets	648		587
Derivative liabilities	225		242
Potential reduction in net position of total derivative liabilities	256		262
Recurring | Prepaid expenses and other current assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	553		333
Recurring | Investments and sundry assets
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	384		585
Recurring | Other accrued expenses and liabilities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative liabilities	366		426
Recurring | Other liabilities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative liabilities	115		78
Recurring | Level 1
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	1,170		1,923
Debt securities - noncurrent	2		2
Available-for-sale equity investments	17		34
Total Assets	1,189		1,959
Recurring | Level 1 | Money market funds
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	1,170		1,923
Recurring | Level 2
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	6,199		5,823
Debt securities - current	799		717
Debt securities - noncurrent	7		8
Available-for-sale equity investments	0
Derivative assets	937		918
Total Assets	7,942		7,466
Total Liabilities	481		503
Recurring | Level 2 | Interest rate contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	392		604
Recurring | Level 2 | Foreign exchange contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	544		305
Derivative liabilities	448		496
Recurring | Level 2 | Equity contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	1		9
Derivative liabilities	33		7
Recurring | Level 2 | Time deposits and certificates of deposit
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	3,532		3,694
Recurring | Level 2 | Commercial paper
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	1,230		2,098
Recurring | Level 2 | U.S. government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	950
Recurring | Level 2 | Canada government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	465
Recurring | Level 2 | Other securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	22		30
Recurring | Total fair value
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	7,369		7,746
Debt securities - current	799		717
Debt securities - noncurrent	9		10
Available-for-sale equity investments	17		34
Derivative assets	937		918
Total Assets	9,131		9,424
Total Liabilities	481		503
Potential reduction in net position of total derivative assets	256		262
Potential reduction in net position of total derivative liabilities	256		262
Recurring | Total fair value | Interest rate contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	392		604
Recurring | Total fair value | Foreign exchange contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	544		305
Derivative liabilities	448		496
Recurring | Total fair value | Equity contracts
Financial assets and financial liabilities measured at fair value on a recurring basis:
Derivative assets	1		9
Derivative liabilities	33		7
Recurring | Total fair value | Time deposits and certificates of deposit
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	3,532		3,694
Recurring | Total fair value | Commercial paper
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	1,230		2,098
Recurring | Total fair value | Money market funds
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	1,170		1,923
Recurring | Total fair value | U.S. government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	950
Recurring | Total fair value | Canada government securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	465
Recurring | Total fair value | Other securities
Financial assets and financial liabilities measured at fair value on a recurring basis:
Cash equivalents	$ 22		$ 30