Loans and Allowance for Loan Losses (Troubled Debt Restructurings) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2016 USD ($) Contract	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2016 USD ($) Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	57	22	112	132
Recorded Investment	$ 14,907,000	$ 7,792,000	$ 30,285,000	$ 40,186,000
Net charge-offs	$ 0	$ 0	$ 0
Total commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	8	7	25	40
Recorded Investment	$ 1,881,000	$ 4,127,000	$ 4,619,000	$ 12,024,000
Total commercial real estate | Investment properties
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	0	1	0	4
Recorded Investment	$ 0	$ 3,370,000	$ 0	$ 5,344,000
Total commercial real estate | 1-4 family properties
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	5	4	21	23
Recorded Investment	$ 964,000	$ 260,000	$ 3,567,000	$ 4,914,000
Total commercial real estate | Land and development
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	3	2	4	13
Recorded Investment	$ 917,000	$ 497,000	$ 1,052,000	$ 1,766,000
Total commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	25	6	54	57
Recorded Investment	$ 10,527,000	$ 3,178,000	$ 22,588,000	$ 25,188,000
Total commercial and industrial | Commercial, financial and agricultural
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	22	5	50	50
Recorded Investment	$ 8,809,000	$ 387,000	$ 20,848,000	$ 19,180,000
Total commercial and industrial | Owner-occupied
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	3	1	4	7
Recorded Investment	$ 1,718,000	$ 2,791,000	$ 1,740,000	$ 6,008,000
Total consumer
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	24	9	33	35
Recorded Investment	$ 2,499,000	$ 487,000	$ 3,078,000	$ 2,974,000
Total consumer | Home equity lines
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	0	2	0	5
Recorded Investment	$ 0	$ 123,000	$ 0	$ 347,000
Total consumer | Consumer mortgages
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	7	0	8	6
Recorded Investment	$ 1,429,000	$ 0	$ 1,438,000	$ 405,000
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	7	25	24
Recorded Investment	$ 1,070,000	$ 364,000	$ 1,640,000	$ 2,222,000
Principal Forgiveness
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 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 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	4,065,000	3,074,000	11,915,000	25,907,000
Below Market Interest Rate | Total commercial real estate
Financing Receivable, Modifications [Line Items]
Recorded Investment	157,000	213,000	2,247,000	5,529,000
Below Market Interest Rate | Total commercial real estate | Investment properties
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	1,826,000
Below Market Interest Rate | Total commercial real estate | 1-4 family properties
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	213,000	2,090,000	3,703,000
Below Market Interest Rate | Total commercial real estate | Land and development
Financing Receivable, Modifications [Line Items]
Recorded Investment	157,000	0	157,000	0
Below Market Interest Rate | Total commercial and industrial
Financing Receivable, Modifications [Line Items]
Recorded Investment	2,978,000	2,791,000	8,738,000	19,406,000
Below Market Interest Rate | Total commercial and industrial | Commercial, financial and agricultural
Financing Receivable, Modifications [Line Items]
Recorded Investment	2,943,000	0	8,703,000	13,948,000
Below Market Interest Rate | Total commercial and industrial | Owner-occupied
Financing Receivable, Modifications [Line Items]
Recorded Investment	35,000	2,791,000	35,000	5,458,000
Below Market Interest Rate | Total consumer
Financing Receivable, Modifications [Line Items]
Recorded Investment	930,000	70,000	930,000	972,000
Below Market Interest Rate | Total consumer | Home equity lines
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	0	0	224,000
Below Market Interest Rate | Total consumer | Consumer mortgages
Financing Receivable, Modifications [Line Items]
Recorded Investment	248,000	0	248,000	354,000
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	682,000	70,000	682,000	394,000
Term Extensions and/or Other Concessions
Financing Receivable, Modifications [Line Items]
Recorded Investment	10,842,000	4,718,000	18,370,000	14,279,000
Term Extensions and/or Other Concessions | Total commercial real estate
Financing Receivable, Modifications [Line Items]
Recorded Investment	1,724,000	3,914,000	2,372,000	6,495,000
Term Extensions and/or Other Concessions | Total commercial real estate | Investment properties
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	3,370,000	0	3,518,000
Term Extensions and/or Other Concessions | Total commercial real estate | 1-4 family properties
Financing Receivable, Modifications [Line Items]
Recorded Investment	964,000	47,000	1,477,000	1,211,000
Term Extensions and/or Other Concessions | Total commercial real estate | Land and development
Financing Receivable, Modifications [Line Items]
Recorded Investment	760,000	497,000	895,000	1,766,000
Term Extensions and/or Other Concessions | Total commercial and industrial
Financing Receivable, Modifications [Line Items]
Recorded Investment	7,549,000	387,000	13,850,000	5,782,000
Term Extensions and/or Other Concessions | Total commercial and industrial | Commercial, financial and agricultural
Financing Receivable, Modifications [Line Items]
Recorded Investment	5,866,000	387,000	12,145,000	5,232,000
Term Extensions and/or Other Concessions | Total commercial and industrial | Owner-occupied
Financing Receivable, Modifications [Line Items]
Recorded Investment	1,683,000	0	1,705,000	550,000
Term Extensions and/or Other Concessions | Total consumer
Financing Receivable, Modifications [Line Items]
Recorded Investment	1,569,000	417,000	2,148,000	2,002,000
Term Extensions and/or Other Concessions | Total consumer | Home equity lines
Financing Receivable, Modifications [Line Items]
Recorded Investment	0	123,000	0	123,000
Term Extensions and/or Other Concessions | Total consumer | Consumer mortgages
Financing Receivable, Modifications [Line Items]
Recorded Investment	1,181,000	0	1,190,000	51,000
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	$ 388,000	$ 294,000	$ 958,000	$ 1,828,000