Fair Value Measurements - Summary of Differences Between Fair Value and Principal Value (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage loans held for sale in loans held for sale	$ 318,272	$ 219,848
Aggregate Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage loans held for sale in loans held for sale	318,272
Past due loans of 90 days or more	0
Nonaccrual loans	0
Aggregate Unpaid Principal Balance
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage loans held for sale in loans held for sale	308,160
Past due loans of 90 days or more	0
Nonaccrual loans	0
Difference
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage loans held for sale in loans held for sale	10,112
Past due loans of 90 days or more	0
Nonaccrual loans	$ 0