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Allowance for Credit Losses - Recorded Investment in Consumer Loan Classes by Performing and Nonperforming Status (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance	$ 7,394,868	$ 7,137,152
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance	1,584,834	$ 1,624,356
Percentage of Total		100.00%
Consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance		$ 1,614,158
Percentage of Total		99.40%
Consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance		$ 10,198
Percentage of Total		0.60%
Consumer | Residential Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance	950,887	$ 998,585
Percentage of Total		100.00%
Consumer | Residential Mortgage | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance		$ 991,066
Percentage of Total		99.20%
Consumer | Residential Mortgage | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance		$ 7,519
Percentage of Total		0.80%
Consumer | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance	537,869	$ 538,348
Percentage of Total		100.00%
Consumer | Home equity | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance		$ 535,709
Percentage of Total		99.50%
Consumer | Home equity | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance		$ 2,639
Percentage of Total		0.50%
Consumer | Installment and other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance	80,735	$ 79,033
Percentage of Total		100.00%
Consumer | Installment and other consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance		$ 78,993
Percentage of Total		99.90%
Consumer | Installment and other consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance		$ 40
Percentage of Total		0.10%
Consumer | Consumer construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance	$ 15,343	$ 8,390
Percentage of Total		100.00%
Consumer | Consumer construction | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance		$ 8,390
Percentage of Total		100.00%
Consumer | Consumer construction | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans held for investment, outstanding balance		$ 0
Percentage of Total		0.00%

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- Definition

Financing receivable gross carrying amount consumer percentage.

+ References

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- Definition

Amount, before allowance for credit loss, of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 79
-URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 326
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-Section 50
-Paragraph 5
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