FAIR VALUE MEASUREMENTS - Estimated Fair Values for All Financial Assets and Liabilities (Detail) - USD ($) $ in Thousands		Jun. 30, 2019	Dec. 31, 2018
Financial assets
Residential mortgages loans	[1]	$ 3,546,468	$ 4,585,975	[2]
Mortgage servicing rights		425,328	557,813	[2]
Interest rate swaps		5,440	48,114
Financial liabilities
Other secured financing		4,127,989	4,183,311	[2]
Securitized debt of consolidated VIEs		3,470,168	3,347,062	[2]
Interest rate swaps		677,295	420,365
Carrying Value | Level 2
Financial assets
Corporate debt, held for investment		1,792,837	1,887,182
Corporate debt held for sale, net		26,906	0
Financial liabilities
Repurchase agreements		105,181,241	81,115,874
Other secured financing		4,127,989	4,183,311
Carrying Value | Level 3
Financial assets
Commercial real estate debt and preferred equity, held for investment (1)		1,413,605	1,296,803
Commercial loans held for sale, net		41,896	42,184
Financial liabilities
Mortgage payable		498,772	511,056
Fair Value | Level 2
Financial assets
Corporate debt, held for investment		1,770,850	1,863,524
Corporate debt held for sale, net		26,906	0
Financial liabilities
Repurchase agreements		105,181,241	81,115,874
Other secured financing		4,128,155	4,183,805
Fair Value | Level 3
Financial assets
Commercial real estate debt and preferred equity, held for investment (1)		1,421,826	1,303,487
Commercial loans held for sale, net		41,896	42,184
Financial liabilities
Mortgage payable		$ 524,723	$ 507,770

[1] ⁽⁴⁾  Includes $119.7 million and $97.5 million of residential mortgage loans held for sale, $41.9 million and $42.2 million of commercial mortgage loans held for sale and $26.9 million and $0 of corporate loans held for sale at June 30, 2019 and December 31, 2018, respectively.

[2] ⁽¹⁾  Derived from the audited consolidated financial statements at December 31, 2018.