Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

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Fair value of investments in debt securities classified as held-to-maturity.

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Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

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Fair Value Measurements - Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017	Oct. 01, 2017	Jan. 01, 2017
Available-for-sale Securities [Abstract]
Available-for-sale Securities - Estimated Fair Value	$ 11,155	$ 5,310
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	16,056	17,824	$ 15,721	$ 18,972
Marketable securities	3,308	$ 472
Held-to-maturity Securities
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities - Carrying Amount	8,209
Held-to-maturity Securities - Estimated Fair Value	8,209
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	8,209
Marketable securities	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0
Held-to-maturity Securities \| Cash
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities - Carrying Amount	2,575
Held-to-maturity Securities - Estimated Fair Value	2,575
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	2,575
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0
Held-to-maturity Securities \| Other sovereign securities(1)
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities - Carrying Amount	0
Held-to-maturity Securities - Estimated Fair Value	0
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	0
Marketable securities
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0
Held-to-maturity Securities \| U.S. reverse repurchase agreements
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities - Carrying Amount	2,260
Held-to-maturity Securities - Estimated Fair Value	2,260
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	2,260
Marketable securities
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0
Held-to-maturity Securities \| Other reverse repurchase agreements
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities - Carrying Amount	479
Held-to-maturity Securities - Estimated Fair Value	479
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	479
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0
Held-to-maturity Securities \| Corporate debt securities(1)
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities - Carrying Amount	200
Held-to-maturity Securities - Estimated Fair Value	200
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	200
Marketable securities	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0
Held-to-maturity Securities \| Money market funds
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities - Carrying Amount	1,763
Held-to-maturity Securities - Estimated Fair Value	1,763
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	1,763
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0
Held-to-maturity Securities \| Time deposits(1)
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities - Carrying Amount	932
Held-to-maturity Securities - Estimated Fair Value	932
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	932
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0
Available-for-sale Securities
Available-for-sale Securities [Abstract]
Available-for-sale Securities - Carrying Amount	11,156
Available-for-sale Securities - Estimated Fair Value	11,155
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	7,847
Marketable securities	3,308
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1
Available-for-sale Securities \| Other sovereign securities(1)
Available-for-sale Securities [Abstract]
Available-for-sale Securities - Carrying Amount	0
Available-for-sale Securities - Estimated Fair Value	0
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	0
Marketable securities	0
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0
Available-for-sale Securities \| Corporate debt securities(1)
Available-for-sale Securities [Abstract]
Available-for-sale Securities - Carrying Amount	271
Available-for-sale Securities - Estimated Fair Value	271
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	12
Marketable securities	259
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0
Available-for-sale Securities \| US Treasury and Government [Member]
Available-for-sale Securities [Abstract]
Available-for-sale Securities - Carrying Amount	10,885
Available-for-sale Securities - Estimated Fair Value	10,884
Available-for-sale Securities and Held-to-maturity Securities [Abstract]
Cash and Cash Equivalents	7,835
Marketable securities	3,049
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ 1