Loans Held for Investment - Purchased Credit Impaired Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Loans Held for Investment
Total purchase credit impaired	$ 9,203	$ 4,559
Commercial and industrial
Loans Held for Investment
Total purchase credit impaired	2,870	2,586
Commercial owner occupied
Loans Held for Investment
Total purchase credit impaired	3,019	491
SBA
Loans Held for Investment
Total purchase credit impaired	334	0
Commercial non-owner occupied
Loans Held for Investment
Total purchase credit impaired	1,303	1,088
Multi-family
Loans Held for Investment
Total purchase credit impaired	226	0
One-to-four family
Loans Held for Investment
Total purchase credit impaired	257	1
Construction
Loans Held for Investment
Total purchase credit impaired	973	0
Other loans
Loans Held for Investment
Total purchase credit impaired	$ 221	$ 393