Fair Value - Aggregate Fair Value and Contractual Balance of Loans for Sale (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Value of loans held for sale	$ 17,513	$ 11,873
Excess	695	311
Contractual Balance
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Value of loans held for sale	$ 16,818	$ 11,562