Contractual interest rate for funds borrowed, under the debt agreement.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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Earliest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer.

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Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value of securities pledged as collateral against securities sold under agreement to repurchase.

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Borrowings - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jan. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Junior subordinated debentures		$ 520
Debt Maturity, Start Year		Jan. 01, 2027
Debt Maturity, End Year		Dec. 31, 2033
Agreements to repurchase securities		$ 419	$ 422
Collateral posted		$ 436	$ 442
Bank Note Program [Member]
Debt Instrument [Line Items]
Senior notes	$ 1,000
Debt instrument maturity year	Jan. 31, 2021
Bank Note Program Fixed Interest Rate [Member]
Debt Instrument [Line Items]
Senior notes	$ 650
Fixed interest rate	2.625%
London Interbank Offered Rate (LIBOR) [Member] \| Bank Note Program Variable Interest Rate [Member]
Debt Instrument [Line Items]
Senior notes	$ 350