Loans Held for Investment - Allowance (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Changes in the allowance for loan losses
Balance, beginning of the year	$ 61,136	$ 59,486
Transition Adjustment CECL	12,562
Provision (reversal of) for credit losses	34,549	951
Loans charged off	(2,035)	(2,300)
Recoveries on charged off loans	527	672
Balance, end of the year	106,739	58,809
Commercial Real Estate
Changes in the allowance for loan losses
Balance, beginning of the year	31,595	27,100
Transition Adjustment CECL	8,073
Provision (reversal of) for credit losses	14,475	(255)
Loans charged off	(214)
Recoveries on charged off loans	10
Balance, end of the year	53,939	26,845
Commercial \| Commercial And Industrial
Changes in the allowance for loan losses
Balance, beginning of the year	17,964	21,980
Transition Adjustment CECL	3,193
Provision (reversal of) for credit losses	18,446	458
Loans charged off	(1,440)	(1,818)
Recoveries on charged off loans	387	648
Balance, end of the year	38,550	21,268
Construction and land development
Changes in the allowance for loan losses
Balance, beginning of the year	4,878	6,061
Transition Adjustment CECL	577
Provision (reversal of) for credit losses	907	(153)
Loans charged off	(2)
Balance, end of the year	6,360	5,908
1 - 4 family residential
Changes in the allowance for loan losses
Balance, beginning of the year	6,386	3,956
Transition Adjustment CECL	(29)
Provision (reversal of) for credit losses	201	389
Loans charged off	(203)	(28)
Recoveries on charged off loans	10	14
Balance, end of the year	6,365	4,331
Consumer
Changes in the allowance for loan losses
Balance, beginning of the year	265	267
Transition Adjustment CECL	748
Provision (reversal of) for credit losses	246	586
Loans charged off	(176)	(454)
Recoveries on charged off loans	120	10
Balance, end of the year	1,203	409
Broker-dealer
Changes in the allowance for loan losses
Balance, beginning of the year	48	122
Provision (reversal of) for credit losses	274	(74)
Balance, end of the year	$ 322	$ 48

Allowance for loan and lease losses adoption of CECL transition adjustment.

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Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount of expense related to estimated loss from loan and lease transactions.

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