Loans - Information Relating to Loans (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES	[1]	$ 3,897,125	$ 3,817,377
Commercial and financial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		616,702	606,014
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		195,788	189,436
Construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		374,244	343,125
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		1,645,239	1,639,992
Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		1,065,152	1,038,810
Portfolio Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES	[1]	3,063,618	2,922,609
Portfolio Loans [Member] | Commercial and financial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		536,321	512,430
Portfolio Loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		188,195	178,826
Portfolio Loans [Member] | Construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		253,416	215,315
Portfolio Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		1,197,152	1,170,618
Portfolio Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		888,534	845,420
PCI Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES	[1]	13,693	17,417
PCI Loans [Member] | Commercial and financial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		819	894
PCI Loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		0	0
PCI Loans [Member] | Construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		1,150	1,121
PCI Loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		9,855	9,776
PCI Loans [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		1,869	5,626
PULs [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES	[1]	819,814	877,351
PULs [Member] | Commercial and financial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		79,562	92,690
PULs [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		7,593	10,610
PULs [Member] | Construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		119,678	126,689
PULs [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		438,232	459,598
PULs [Member] | Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
NET LOAN BALANCES		$ 174,749	$ 187,764

[1] Net loan balances as of March 31, 2018 and December 31, 2017 include deferred costs of $13.9 million and $12.9 million for each period, respectively.