Supplemental Cash Flow Information - Additional Information (Detail) $ in Billions	12 Months Ended
Dec. 31, 2020 USD ($)
Supplemental Cash Flow Elements [Abstract]
Repayment of loans related to life insurance policies	$ 112.3

Net amount paid or received by the entity associated with issuance or collection of loans made to policy holders, principally secured by the benefits under the policy.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690

Name:	us-gaap_PaymentsForProceedsFromPolicyLoans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration