Summary of Financial Information for Closed Block (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Liabilities:
Future policyholder benefits	$ 1,533	$ 1,571
Policyholder funds and accumulated dividends	136	137
Policyholder dividends payable	18	20
Policyholder dividend obligation	35	110
Other policy obligations and liabilities	38	25
Total liabilities	1,760	1,863
Assets:
Available-for-sale securities	1,202	1,294
Mortgage loans, net of allowance	220	220
Policy loans	124	128
Other assets	80	77
Total assets	1,626	1,719
Excess of reported liabilities over assets	134	144
Portion of above representing other comprehensive income:
(Decrease) Increase in unrealized gain on fixed maturity securities, available-for-sale	(67)	14
Adjustment to policyholder dividend obligation	67	(14)
Total of above representing other than comprehensive income	0	0
Maximum future earnings to be recognized from assets and liabilities	134	144	$ 153	$ 162
Available-for-sale securities:
Fair value	1,202	1,294
Amortized cost	1,181	1,206
Shadow policyholder dividend obligation	(21)	(88)
Net unrealized appreciation	$ 0	$ 0

Closed block policy holder fund and accumulated dividend.

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Fixed Maturity Securities Available for Sale [Abstract]

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Shadow policyholder dividend obligation.

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The sum of cash, cash equivalents, investments and other assets allocated to the segregated group of participating or dividend-paying policies and contracts identified as the closed block.

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Carrying amount of investments in debt securities that are deemed to be held to maturity that are allocated to the segregated group of participating or dividend-paying policies and contracts identified as the closed block.

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Fair value of investments in debt securities that are deemed to be available for sale that are allocated to the segregated group of participating or dividend-paying policies and contracts identified as the closed block. Change in fair of such securities is a component of change in other comprehensive income in the period, which is reflected in the closed block disclosure.

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Carrying amount of investments in mortgage loans on real estate allocated to the segregated group of participating or dividend-paying policies and contracts identified as the closed block.

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Amount of other assets held by the closed block. Excludes other investments.

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Carrying amount of loans to policy holders secured by benefits under insurance policies that are allocated to the segregated group of participating or dividend-paying policies and contracts identified as the closed block.

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Short-term investments allocated to the segregated group of participating or dividend-paying policies and contracts identified as the closed block.

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For the segregated group of participating or dividend-paying policies and contracts identified as the closed block, the change in the period in the obligation representing amounts to be distributed to policyholders owning contracts in the closed block. Also a component of change in other comprehensive income in the period, which is reflected in the closed block disclosure.

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The increase or decrease in the period in other comprehensive income within the closed block comprised of the change in (a) dividend obligation to policyholders of the closed block, and (b) unrealized gain (loss) on available for sale securities allocated to the closed block.

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The carrying amount of closed block liabilities in excess of the carrying amount of closed block assets at the date of demutualization (adjusted to eliminate the impact of related amounts in accumulated other comprehensive income).

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The net increase or decrease in the period in the fair value of the fixed maturity and equity investments designated as available for sale as of the balance sheet date that were allocated to the segregated group of participating or dividend-paying policies and contracts identified as a closed block. Also a component of change in other comprehensive income in the period, which is reflected in the closed block disclosure.

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For the segregated group of participating or dividend-paying policies and contracts along with the assets backing them (known as a closed block), the total of future policy benefits, policyholder account balance, policyholder dividend obligation and any other closed block liabilities.

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The liability as of the balance sheet date for future benefits to be paid to or on behalf of policyholders and expenses, less the present value of future net premiums payable under the insurance contracts and the policy cash accumulations, for the segregated group of participating or dividend-paying policies and contracts identified as a closed block.

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Amount of liabilities allocated to the closed block, classified as other.

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The liability as of the balance sheet date for the excess of the cumulative actual closed block earnings over the cumulative expected (actuarially determined) closed block earnings (each) for the period from the actuarial calculation date to the date of measurement. The excess will result in future dividends to closed block policyholders, unless offset by less favorable than expected future performance of the closed block. The policyholder dividend obligation, which may not have a negative balance, recognizes that a portion of earnings in certain cases will not inure to the stockholders of the insurance entity.

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Amount of dividends payable as of the balance sheet date to policyholders of contracts in the closed block.

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The difference between the liabilities of and the assets allocated to the segregated group of participating or dividend-paying policies and contracts identified as the closed block.

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