FAIR VALUE MEASUREMENT - Schedule of Inputs Used in Valuing Residential Mortgage Loans (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Mortgage Loans on Real Estate [Line Items]
Weighted Average Life (Years)		1 year 10 months 3 days
Performing Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Weighted Average Life (Years)	[1],[2]		6 years 8 months
Nonrecurring [Member]
Mortgage Loans on Real Estate [Line Items]
Discount Rate		4.90%	5.60%
Weighted Average Life (Years)	[3]	4 years 1 month 5 days	3 years 7 months 7 days
Prepayment Rate		6.10%	4.20%
Loss Severity	[4]	27.90%	22.70%
Nonrecurring [Member] | Performing Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Discount Rate		3.80%	5.00%
Weighted Average Life (Years)	[3]	5 years 11 months 19 days	4 years 2 months 18 days
Prepayment Rate		11.70%	9.20%
CDR	[5]	1.20%	2.80%
Loss Severity	[4]	24.40%	35.20%
Nonrecurring [Member] | Non-Performing Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Discount Rate		5.60%	5.70%
Weighted Average Life (Years)	[3]	2 years 11 months 25 days	3 years 5 months 12 days
Prepayment Rate		2.80%	2.90%
Loss Severity	[4]	30.00%	19.60%
Nonrecurring [Member] | Fair Value [Member]
Mortgage Loans on Real Estate [Line Items]
Fair Value		$ 406,284	$ 253,013
Nonrecurring [Member] | Fair Value [Member] | Performing Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Fair Value		151,436	50,858
Nonrecurring [Member] | Fair Value [Member] | Non-Performing Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Fair Value		$ 254,848	$ 202,155

[1] Performing loans are generally placed on nonaccrual status when principal or interest is 120 days or more past due.

[2] The weighted average life is based on the expected timing of the receipt of cash flows.

[3] The weighted average life is based on the expected timing of the receipt of cash flows.

[4] Loss severity is the expected amount of future realized losses resulting from the ultimate liquidation of a particular loan, expressed as the net amount of loss relative to the outstanding loan balance.

[5] Represents the annualized rate of the involuntary prepayments (defaults) as a percentage of the total principal balance.