Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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

Organization - Narrative (Details) $ in Thousands	3 Months Ended
Organization - Narrative (Details) $ in Thousands	Mar. 31, 2021 USD ($) bank_branch	Dec. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)
Business Acquisition [Line Items]
Retained earnings \| $	$ 559,797	$ 409,391
Allowance for credit losses \| $	383,016	433,752	$ 274,863	$ 181,973	$ 174,646
Goodwill impairment \| $	$ 0	$ 0	$ 1,470,000
CALIFORNIA
Business Acquisition [Line Items]
Retail branch locations \| bank_branch	70
NORTH CAROLINA
Business Acquisition [Line Items]
Retail branch locations \| bank_branch	1
COLORADO
Business Acquisition [Line Items]
Retail branch locations \| bank_branch	1