Loans and Allowance for Credit Losses (Troubled Debt Restructurings Modified by Portfolio Segment) (Details) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($) contract	Dec. 31, 2018 USD ($) contract	Dec. 31, 2017 USD ($) contract
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	49	56	78
Pre-Modification Outstanding Recorded Investment	$ 68,118	$ 94,760	$ 177,070
Post-Modification Outstanding Recorded Investment	$ 61,307	$ 94,760	$ 177,070
Total Commercial [Member] \| Commercial Real Estate - Income Producing [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	1	1	5
Pre-Modification Outstanding Recorded Investment	$ 123	$ 1,564	$ 5,625
Post-Modification Outstanding Recorded Investment	$ 123	$ 1,564	$ 5,625
Total Commercial [Member] \| Construction and Land Development [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	3
Pre-Modification Outstanding Recorded Investment	$ 323
Post-Modification Outstanding Recorded Investment	$ 323
Residential Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	21	14	15
Pre-Modification Outstanding Recorded Investment	$ 3,286	$ 1,297	$ 2,812
Post-Modification Outstanding Recorded Investment	$ 3,286	$ 1,297	$ 2,812
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	10	10	1
Pre-Modification Outstanding Recorded Investment	$ 168	$ 455	$ 40
Post-Modification Outstanding Recorded Investment	$ 168	$ 455	$ 40
Total Commercial And Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	14	31	57
Pre-Modification Outstanding Recorded Investment	$ 64,218	$ 91,444	$ 168,593
Post-Modification Outstanding Recorded Investment	$ 57,407	$ 91,444	$ 168,593
Total Commercial And Industrial [Member] \| Total Commercial [Member] \| Commercial Non-Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	13	29	52
Pre-Modification Outstanding Recorded Investment	$ 64,051	$ 85,306	$ 162,909
Post-Modification Outstanding Recorded Investment	$ 57,240	$ 85,306	$ 162,909
Total Commercial And Industrial [Member] \| Total Commercial [Member] \| Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts \| contract	1	2	5
Pre-Modification Outstanding Recorded Investment	$ 167	$ 6,138	$ 5,684
Post-Modification Outstanding Recorded Investment	$ 167	$ 6,138	$ 5,684

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524

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