Summary of Changes in DAC Balance (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred Policy Acquisition Costs
Balance at beginning of year	$ 5,676	$ 5,432	$ 5,200
Capitalization of DAC	942	923	823
Amortization of DAC, excluding unlocks	(440)	(461)	(412)
Amortization of DAC related to unlocks	17	69	(21)
Adjustments to DAC related to unrealized gains and losses on available-for-sale securities	635	(287)	(158)
Balance at end of year	$ 6,830	$ 5,676	$ 5,432

Deferred policy acquisition cost amortization expense excluding unlock.

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- Definition

Amount of amortization expense (reversal of amortization expense) of deferred policy acquisition costs from a revision in estimated gross profit or estimated gross margin.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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- Definition

Amount of unrealized investment gain (loss) which decreases (increases) deferred policy acquisition cost.

+ References

No definition available.

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- Definition

Net amount of deferred policy acquisition costs capitalized on contracts remaining in force as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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- Definition

Total amount of policy acquisition costs capitalized during the income statement period.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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