Loans Held for Investment and Allowance for Loan Losses (Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	$ 889,303	$ 543,790
Net deferred origination costs	16,024	8,952
Total loans held for investment	905,327	552,742
Term loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	783,803	482,596
Lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total unpaid principal balance	$ 105,500	$ 61,194