Fair Value Measurements - Amount of Net Gains (Losses) from Fair Value Changes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Mortgage loans held for sale, at fair value	$ 2,486	$ (251)	$ 944
Mortgage loans held for investment, at fair value	$ 18	$ (1,542)	$ (204)