SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Accretion and Other Amortization (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accretion of discount and other amortization:
Accretion of servicer advance interest income		$ 364,350	$ 352,316	$ 190,206
Accretion of excess mortgage servicing rights income		150,141	134,565	49,180
Accretion of net discount on securities and loans	[1]	253,243	65,925	47,793
Amortization of deferred financing costs		(18,326)	(26,036)	(8,771)
Amortization of discount on notes and bonds payable		(1,476)	(1,472)	0
Accretion and other amortization		$ 747,932	$ 525,298	$ 278,408

[1] Includes accretion of the accretable yield on PCD loans.