Acquisition - Acquired Loans at Acquisition Date (Details) - USD ($) $ in Thousands	Sep. 13, 2013	Jan. 01, 2015
Loans excluding PCI Loans | Commercial and industrial
Information about the acquired loans at acquisition
Margin loans to customers and correspondents		$ 269,400
SWS
Information about the acquired loans at acquisition
Total loans		863,819
SWS | Commercial and industrial
Information about the acquired loans at acquisition
Total loans		457,809
SWS | Real estate
Information about the acquired loans at acquisition
Total loans		386,695
SWS | Construction and land development
Information about the acquired loans at acquisition
Total loans		16,099
SWS | Consumer
Information about the acquired loans at acquisition
Total loans		3,216
SWS | Loans excluding PCI Loans
Information about the acquired loans at acquisition
Total loans		790,360
SWS | Loans excluding PCI Loans | Commercial and industrial
Information about the acquired loans at acquisition
Total loans		447,959
SWS | Loans excluding PCI Loans | Real estate
Information about the acquired loans at acquisition
Total loans		324,477
SWS | Loans excluding PCI Loans | Construction and land development
Information about the acquired loans at acquisition
Total loans		14,708
SWS | Loans excluding PCI Loans | Consumer
Information about the acquired loans at acquisition
Total loans		3,216
SWS | PCI loans
Information about the acquired loans at acquisition
Total loans		73,459
SWS | PCI loans | Commercial and industrial
Information about the acquired loans at acquisition
Total loans		9,850
SWS | PCI loans | Real estate
Information about the acquired loans at acquisition
Total loans		62,218
SWS | PCI loans | Construction and land development
Information about the acquired loans at acquisition
Total loans		$ 1,391
Bank | FNB
Information about the acquired loans at acquisition
Carryover of Allowance for Loan and Lease Losses, Loans Acquired	$ 0
Total loans	1,159,467
Bank | FNB | Commercial and industrial
Information about the acquired loans at acquisition
Total loans	95,625
Bank | FNB | Real estate
Information about the acquired loans at acquisition
Total loans	854,217
Bank | FNB | Construction and land development
Information about the acquired loans at acquisition
Total loans	184,916
Bank | FNB | Consumer
Information about the acquired loans at acquisition
Total loans	24,709
Bank | FNB | Loans excluding PCI Loans
Information about the acquired loans at acquisition
Total loans	336,636
Bank | FNB | Loans excluding PCI Loans | Commercial and industrial
Information about the acquired loans at acquisition
Total loans	47,874
Bank | FNB | Loans excluding PCI Loans | Real estate
Information about the acquired loans at acquisition
Total loans	242,998
Bank | FNB | Loans excluding PCI Loans | Construction and land development
Information about the acquired loans at acquisition
Total loans	26,669
Bank | FNB | Loans excluding PCI Loans | Consumer
Information about the acquired loans at acquisition
Total loans	19,095
Bank | FNB | PCI loans
Information about the acquired loans at acquisition
Total loans	822,831
Bank | FNB | PCI loans | Commercial and industrial
Information about the acquired loans at acquisition
Total loans	47,751
Bank | FNB | PCI loans | Real estate
Information about the acquired loans at acquisition
Total loans	611,219
Bank | FNB | PCI loans | Construction and land development
Information about the acquired loans at acquisition
Total loans	158,247
Bank | FNB | PCI loans | Consumer
Information about the acquired loans at acquisition
Total loans	$ 5,614