Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.(a),6)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99397103&loc=d3e6824-158387

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99404803&loc=d3e21409-158489

Name:	us-gaap_ReinsuranceRecoverables
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

REINSURANCE Additional Information (Detail) $ in Millions, ¥ in Billions	12 Months Ended
	Dec. 31, 2018 JPY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Effects of Reinsurance [Line Items]
Percent change in spot yen/dollar exchange rate		2.00%
Percent change in ceded reserves		2.00%
Aflac Japan
Effects of Reinsurance [Line Items]
Committed reinsurance facility \| ¥	¥ 110
Aflac Japan \| Closed block
Effects of Reinsurance [Line Items]
Reinsurance deferred profit liability		$ 1,000
Reinsurance recoverable		$ 941	$ 908