The cumulative amount of the reporting entity's undistributed earnings or deficit.

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Name:	us-gaap_RetainedEarningsAccumulatedDeficit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Credit Losses - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Cumulative effect of accounting changes, net of tax	$ 241,583		$ 173,371
Accounting Standards Update 2016-13 [Member] \| Revision of Prior Period, Adjustment [Member]
Financing Receivable, Past Due [Line Items]
Cumulative Effect on Retained Earnings, Tax		$ 400
Accounting Standards Update 2016-13 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Past Due [Line Items]
Cumulative effect of accounting changes, net of tax		$ 1,200