Organization and Summary of Significant Accounting Policies - Schedule of Loans Receivable Held-for-sale (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loans Receivable Held-for-sale, Net, Reconciliation to Cash Flow [Roll Forward]
Balance at beginning of year	$ 966,447	$ 687,393
Originations	1,183,152	1,005,165	$ 1,079,472
Proceeds from sale	(875,393)	(457,533)	(1,086,614)
Gain on sale of loans	49,473	29,002	75,170
Principal collections, net of deferred fees and costs	50,431	(58,683)
Non-cash transfers, net	(198,640)	(238,897)
Balance at end of period	$ 1,175,470	$ 966,447	$ 687,393