Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended
Mar. 31, 2020	Jan. 01, 2020
Summary Of Significant Accounting Policies [Line Items]
Net decrease in retained earnings		$ 1,300,000
Transition adjustment, allowance for credit loses for loans	$ 1,800,000
Adjustment of transition reserve for loans	41,000
Increase in provision for credit loses	$ 12,000,000

Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794

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