Fair Value Measurements Notional Amount of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Notional Disclosures [Abstract]
Best efforts contracts and related committed IRLCs	$ 5,823	$ 2,182
Uncommitted IRLCs	76,117	50,746
FMBSs related to uncommitted IRLCs	83,000	53,000
Best efforts contracts and related mortgage loans held for sale	14,285	80,956
FMBSs related to mortgage loans held for sale	150,000	91,000
Mortgage loans held for sale covered by FMBSs	$ 149,980	$ 90,781