Fair Value Measurements Notional Amount of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Notional Disclosures [Abstract]
Best efforts contracts and related committed IRLCs	$ 2,571	$ 6,607
Uncommitted IRLCs	105,104	66,875
FMBSs related to uncommitted IRLCs	105,000	66,000
Best efforts contracts and related mortgage loans held for sale	10,423	125,348
FMBSs related to mortgage loans held for sale	81,000	33,000
Mortgage loans held for sale covered by FMBSs	$ 81,244	$ 32,870