OTHER INCOME (LOSS), GENERAL AND ADMINISTRATIVE, OTHER ASSETS AND LIABILITIES - Schedule of General and Administrative Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Schedule Of Other Income [Line Items]
Legal and professional expense	$ 15,552	$ 16,618	$ 41,589	$ 29,910
Loan origination expense	23,635	14,198	46,035	24,467
Occupancy expense	8,775	4,786	16,839	8,965
Other	36,765	14,483	74,008	29,072
General and Administrative Expense	217,373	118,906	423,736	217,846
Servicing
Schedule Of Other Income [Line Items]
Compensation and benefits expense	59,498	29,480	110,839	54,781
Origination
Schedule Of Other Income [Line Items]
Compensation and benefits expense	$ 73,148	$ 39,341	$ 134,426	$ 70,651