Fair Value of Financial Instruments - Fair value, assets measure on recurring basis, unobservable inputs (Details) - Mortgage loans at fair value and loans held-for-sale - Level 3, Unobservable Inputs - Loans receivable - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Mortgage loans at fair value based on Level 3 inputs, beginning balance	$ 4,848	$ 8,072
Net gain on mortgage loans	531	1,771
Mortgage loan dispositions, resolutions and payments	(660)	(1,760)
Real estate tax advances to borrowers	17	29
Transfer of mortgage loans to real estate owned, net	(364)	(3,740)
Mortgage loans at fair value based on Level 3 inputs, ending balance	4,372	4,372
Change in unrealized gain on mortgage loans at fair value based on Level 3 inputs held at the end of the period	$ 187	$ 189