Loans and Allowance for Loan Losses (Troubled Debt Restructurings) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) Contract	Jun. 30, 2017 USD ($) Contract	Jun. 30, 2018 USD ($) Contract	Jun. 30, 2017 USD ($) Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	42	26	81	55
Recorded Investment	$ 15,878,000	$ 3,770,000	$ 25,365,000	$ 15,377,000
Net charge-offs	$ 0	$ 0	$ 0	$ 0
Total commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	9	11	20	29
Recorded Investment	$ 3,262,000	$ 2,657,000	$ 7,048,000	$ 12,061,000
Total commercial and industrial | Commercial, financial and agricultural
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	5	10	14	28
Recorded Investment	$ 576,000	$ 2,635,000	$ 1,565,000	$ 12,039,000
Total commercial and industrial | Owner-occupied
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	4	1	6	1
Recorded Investment	$ 2,686,000	$ 22,000	$ 5,483,000	$ 22,000
Total commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	6	9	13	17
Recorded Investment	$ 8,545,000	$ 809,000	$ 11,469,000	$ 2,737,000
Total commercial real estate | Investment properties
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	2	0	3	0
Recorded Investment	$ 6,267,000	$ 0	$ 8,226,000	$ 0
Total commercial real estate | 1-4 family properties
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	1	8	7	16
Recorded Investment	$ 492,000	$ 674,000	$ 1,457,000	$ 2,602,000
Total commercial real estate | Land and development
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	3	1	3	1
Recorded Investment	$ 1,786,000	$ 135,000	$ 1,786,000	$ 135,000
Total consumer
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	27	6	48	9
Recorded Investment	$ 4,071,000	$ 304,000	$ 6,848,000	$ 579,000
Total consumer | Home equity lines
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	3	0	3	0
Recorded Investment	$ 320,000	$ 0	$ 320,000	$ 0
Total consumer | Consumer mortgages
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	7	1	14	1
Recorded Investment	$ 3,050,000	$ 9,000	$ 4,782,000	$ 9,000
Total consumer | Credit cards
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	0	0	0	0
Recorded Investment	$ 0	$ 0	$ 0	$ 0
Total consumer | Other consumer loans
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	17	5	31	8
Recorded Investment	$ 701,000	$ 295,000	$ 1,746,000	$ 570,000
Principal Forgiveness
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total commercial and industrial
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total commercial and industrial | Commercial, financial and agricultural
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total commercial and industrial | Owner-occupied
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total commercial real estate
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total commercial real estate | Investment properties
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total commercial real estate | 1-4 family properties
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total commercial real estate | Land and development
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total consumer
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total consumer | Home equity lines
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total consumer | Consumer mortgages
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total consumer | Credit cards
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Principal Forgiveness | Total consumer | Other consumer loans
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Below Market Interest Rate
Financing Receivable, Modifications [Line Items]
Recorded Investment	11,628,000	2,373,000	17,567,000	7,849,000
Below Market Interest Rate | Total commercial and industrial
Financing Receivable, Modifications [Line Items]
Recorded Investment	2,094,000	1,895,000	4,799,000	5,760,000
Below Market Interest Rate | Total commercial and industrial | Commercial, financial and agricultural
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	1,895,000	0	5,760,000
Below Market Interest Rate | Total commercial and industrial | Owner-occupied
Financing Receivable, Modifications [Line Items]
Recorded Investment	2,094,000	0	4,799,000	0
Below Market Interest Rate | Total commercial real estate
Financing Receivable, Modifications [Line Items]
Recorded Investment	6,011,000	478,000	6,976,000	2,089,000
Below Market Interest Rate | Total commercial real estate | Investment properties
Financing Receivable, Modifications [Line Items]
Recorded Investment	6,011,000	0	6,011,000	0
Below Market Interest Rate | Total commercial real estate | 1-4 family properties
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	478,000	965,000	2,089,000
Below Market Interest Rate | Total commercial real estate | Land and development
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Below Market Interest Rate | Total consumer
Financing Receivable, Modifications [Line Items]
Recorded Investment	3,523,000	0	5,792,000	0
Below Market Interest Rate | Total consumer | Home equity lines
Financing Receivable, Modifications [Line Items]
Recorded Investment	172,000	0	172,000	0
Below Market Interest Rate | Total consumer | Consumer mortgages
Financing Receivable, Modifications [Line Items]
Recorded Investment	2,963,000	0	4,695,000	0
Below Market Interest Rate | Total consumer | Credit cards
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Below Market Interest Rate | Total consumer | Other consumer loans
Financing Receivable, Modifications [Line Items]
Recorded Investment	388,000	0	925,000	0
Term Extensions and/or Other Concessions
Financing Receivable, Modifications [Line Items]
Recorded Investment	4,250,000	1,397,000	7,798,000	7,528,000
Term Extensions and/or Other Concessions | Total commercial and industrial
Financing Receivable, Modifications [Line Items]
Recorded Investment	1,168,000	762,000	2,249,000	6,301,000
Term Extensions and/or Other Concessions | Total commercial and industrial | Commercial, financial and agricultural
Financing Receivable, Modifications [Line Items]
Recorded Investment	576,000	740,000	1,565,000	6,279,000
Term Extensions and/or Other Concessions | Total commercial and industrial | Owner-occupied
Financing Receivable, Modifications [Line Items]
Recorded Investment	592,000	22,000	684,000	22,000
Term Extensions and/or Other Concessions | Total commercial real estate
Financing Receivable, Modifications [Line Items]
Recorded Investment	2,534,000	331,000	4,493,000	648,000
Term Extensions and/or Other Concessions | Total commercial real estate | Investment properties
Financing Receivable, Modifications [Line Items]
Recorded Investment	256,000	0	2,215,000	0
Term Extensions and/or Other Concessions | Total commercial real estate | 1-4 family properties
Financing Receivable, Modifications [Line Items]
Recorded Investment	492,000	196,000	492,000	513,000
Term Extensions and/or Other Concessions | Total commercial real estate | Land and development
Financing Receivable, Modifications [Line Items]
Recorded Investment	1,786,000	135,000	1,786,000	135,000
Term Extensions and/or Other Concessions | Total consumer
Financing Receivable, Modifications [Line Items]
Recorded Investment	548,000	304,000	1,056,000	579,000
Term Extensions and/or Other Concessions | Total consumer | Home equity lines
Financing Receivable, Modifications [Line Items]
Recorded Investment	148,000	0	148,000	0
Term Extensions and/or Other Concessions | Total consumer | Consumer mortgages
Financing Receivable, Modifications [Line Items]
Recorded Investment	87,000	9,000	87,000	9,000
Term Extensions and/or Other Concessions | Total consumer | Credit cards
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	0
Term Extensions and/or Other Concessions | Total consumer | Other consumer loans
Financing Receivable, Modifications [Line Items]
Recorded Investment	$ 313,000	$ 295,000	$ 821,000	$ 570,000