Marketable Securities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Marketable Securities [Line Items]
Total Marketable Securities	$ 8,029		$ 8,029		$ 9,222
Total Cash and Cash Equivalents	15,433		15,433		18,954
Total Restricted Cash and Marketable Securities	2,112		2,112		2,273
Available-for-sale Securities, Due in one year or less	12,273		12,273
Available-for-sale Securities, Due between one year and five years	1,945		1,945
Total available-for-sale securities with contractual maturities	14,218		14,218
Sales proceeds from investments classified as available-for-sale and sold prior to maturity	1,100	$ 663	7,000	$ 2,100
Cash And Cash Equivalents [Member]
Marketable Securities [Line Items]
Available-for-sale Securities	7,767		7,767		10,890
Trading Securities	13		13		431
Total Marketable Securities	7,780		7,780		11,321
Cash, Cash Equivalents And Time Deposits	7,653		7,653		7,633
Cash And Cash Equivalents [Member] | Level 1 [Member] | Money Market Funds [Member]
Marketable Securities [Line Items]
Available-for-sale Securities	909		909		2,480
Cash And Cash Equivalents [Member] | Level 2 [Member] | U.S. government and agencies [Member]
Marketable Securities [Line Items]
Available-for-sale Securities	150		150		1,600
Cash And Cash Equivalents [Member] | Level 2 [Member] | Sovereign Debt [Member]
Marketable Securities [Line Items]
Available-for-sale Securities	2,468		2,468		774
Cash And Cash Equivalents [Member] | Level 2 [Member] | Corporate debt [Member]
Marketable Securities [Line Items]
Available-for-sale Securities	4,240		4,240		6,036
Cash And Cash Equivalents [Member] | Level 2 [Member] | Sovereign and Corporate Debt [Member]
Marketable Securities [Line Items]
Trading Securities	13		13		431
Marketable Securities [Member]
Marketable Securities [Line Items]
Available-for-sale Securities	7,334		7,334		7,955
Trading Securities	695		695		1,267
Marketable Securities [Member] | Level 2 [Member] | U.S. government and agencies [Member]
Marketable Securities [Line Items]
Available-for-sale Securities	5,088		5,088		5,957
Marketable Securities [Member] | Level 2 [Member] | Sovereign Debt [Member]
Marketable Securities [Line Items]
Trading Securities	695		695		1,267
Marketable Securities [Member] | Level 2 [Member] | Corporate debt [Member]
Marketable Securities [Line Items]
Available-for-sale Securities	2,246		2,246		1,998
Restricted cash and marketable securities [Member]
Marketable Securities [Line Items]
Available-for-sale Securities	1,318		1,318		1,427
Restricted cash, cash equivalents and time deposits	794		794		846
Restricted cash and marketable securities [Member] | Level 1 [Member] | Money Market Funds [Member]
Marketable Securities [Line Items]
Available-for-sale Securities	$ 1,318		$ 1,318		$ 1,427