Loans Held for Investment - Components of Impaired Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Receivables [Abstract]
Nonaccruing loans	$ 3,054	$ 2,736	$ 2,742
Accruing loans	0	48	180
Total impaired loans	$ 3,054	$ 2,784	$ 2,922