Fair Value Measurements Notional Amount of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Notional Disclosures [Abstract]
Whole loan contracts and related committed IRLCs	$ 4,287	$ 5,823
Uncommitted IRLCs	111,399	76,117
FMBSs related to uncommitted IRLCs	110,000	83,000
Whole loan contracts and related mortgage loans held for sale	6,325	14,285
FMBSs related to mortgage loans held for sale	111,000	150,000
Mortgage loans held for sale covered by FMBSs	$ 111,510	$ 149,980