Fair Value Measurements - Summarizes Differences Between Fair Value and Principal Balance for Mortgage Loans Held for Sale Measure at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Aggregate Fair Value
Summarizes differences between fair value and principal balance for mortgage loans held for sale measure at fair value
Mortgage loans held for sale measured at fair value	$ 502,002	$ 417,771
Aggregate Unpaid Principal Balance
Summarizes differences between fair value and principal balance for mortgage loans held for sale measure at fair value
Mortgage loans held for sale measured at fair value	492,064	395,602
Difference
Summarizes differences between fair value and principal balance for mortgage loans held for sale measure at fair value
Mortgage loans held for sale measured at fair value	$ 9,938	$ 22,169