Fair Value Measurements Notional Amount of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Notional Disclosures [Abstract]
Whole loan contracts and related committed IRLCs	$ 1,375	$ 2,354
Uncommitted IRLCs	366,998	208,500
FMBSs related to uncommitted IRLCs	337,000	183,000
Whole loan contracts and related mortgage loans held for sale	16,959	78,142
FMBSs related to mortgage loans held for sale	194,000	131,000
Mortgage loans held for sale covered by FMBSs	$ 198,486	$ 148,331