DEBT OBLIGATIONS - Narrative (Details)			1 Months Ended	3 Months Ended	12 Months Ended
		Oct. 02, 2015 USD ($)	Oct. 31, 2016 USD ($) Class	Sep. 30, 2015 USD ($)	Dec. 31, 2016 USD ($) agreement		Dec. 31, 2015 USD ($)		Dec. 31, 2014 USD ($)		Oct. 13, 2015 USD ($)	Oct. 01, 2015 USD ($)
Debt Instrument [Line Items]
Debt instrument, face amount					$ 13,208,783,000
Debt					13,181,236,000	[1]	$ 11,292,622,000	[1]	$ 6,057,853,000	[2]
Amount released from restricted cash accounts					$ (74,604,000)		0		$ 0
Percent decline in equity, first period					50.00%
Decline in equity, first period (in months)					12 months
Percent decline in equity, second period					35.00%
Decline in equity, second period (in months)					3 months
Ratio of indebtedness to tangible net worth					4
HSART [Member]
Debt Instrument [Line Items]
Surplus servicer advance commitments				$ 4,000,000,000
Amount released from restricted cash accounts		$ 92,700,000
HSART [Member] | General and Administrative Expense [Member]
Debt Instrument [Line Items]
Liability for settlement agreement											$ 9,100,000
Term Notes [Member] | HSART [Member]
Debt Instrument [Line Items]
Debt		$ 2,500,000,000										$ 2,500,000,000
Repurchase Agreements [Member] | Total Repurchase Agreements [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	[3]				$ 5,193,686,000
Debt	[1],[3]				$ 5,190,631,000		$ 4,043,054,000
Secured Debt [Member] | Asset-backed Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 79,900,000.0
Secured Debt [Member] | Asset-backed Notes [Member] | Consumer Loan Companies [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			1,700,000,000.0
Amount voluntarily retained			157,600,000
Loss on extinguishment of debt			$ 4,700,000
Number of classes of debt | Class			6
Stockholders' Equity, Total [Member] | Counterpary Concentration Risk Exceeding 10% [Member] | Repurchase Agreements [Member]
Debt Instrument [Line Items]
Number of outstanding repurchase agreements | agreement					0

[1] Net of deferred financing costs.

[2] Excludes debt related to linked transactions (Note 10).

[3] These repurchase agreements had approximately $11.0 million of associated accrued interest payable as of December 31, 2016.