Fair Value Measurements - Measured on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Assets
Derivatives	$ 22	$ 23
Liabilities
Derivatives	61	106
Mutual funds
Assets
Fair value of investments measured on recurring basis	978	917
U.S. Government securities
Assets
Fair value of investments measured on recurring basis	105	116
Other securities
Assets
Fair value of investments measured on recurring basis	144	209
Level 1
Assets
Derivatives	0	0
Liabilities
Derivatives	0	0
Level 1 \| Mutual funds
Assets
Fair value of investments measured on recurring basis	978	917
Level 1 \| U.S. Government securities
Assets
Fair value of investments measured on recurring basis	0	0
Level 1 \| Other securities
Assets
Fair value of investments measured on recurring basis	28	39
Level 2
Assets
Derivatives	22	23
Liabilities
Derivatives	61	106
Level 2 \| Mutual funds
Assets
Fair value of investments measured on recurring basis	0	0
Level 2 \| U.S. Government securities
Assets
Fair value of investments measured on recurring basis	105	116
Level 2 \| Other securities
Assets
Fair value of investments measured on recurring basis	116	170
NAV \| Other commingled funds
Liabilities
Alternative Investment	$ 18	$ 19

Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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