Fair Value Measurements Notional Amount of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Notional Disclosures [Abstract]
Whole loan contracts and related committed IRLCs	$ 2,924	$ 1,445
Uncommitted IRLCs	213,146	87,340
FMBSs related to uncommitted IRLCs	186,000	88,000
Whole loan contracts and related mortgage loans held for sale	13,750	6,125
FMBSs related to mortgage loans held for sale	116,000	144,000
Mortgage loans held for sale covered by FMBSs	$ 120,257	$ 144,411