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	9 Months Ended
	Sep. 30, 2019	Sep. 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	$ 4,372	$ 8,072
Net gain (loss) on mortgage loans	(1,759)	12
Mortgage loan dispositions, resolutions and payments	1,355	(405)
Real estate tax advances to borrowers	36	65
Transfer of mortgage loans to real estate owned, net	(391)	(4,131)
Transfers out of Level 3	(3,613)	(3,613)
Mortgage loans at fair value based on Level 3 inputs, ending balance	$ 0	$ 0