Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE MEASUREMENT - Schedule of Inputs Used In Valuing Residential Mortgage Loans, Derivatives, and Mortgage Backed Securities (Details)

v3.10.0.1
FAIR VALUE MEASUREMENT - Schedule of Inputs Used In Valuing Residential Mortgage Loans, Derivatives, and Mortgage Backed Securities (Details)
$ in Thousands
Sep. 30, 2018
USD ($)
Dec. 31, 2017
USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities, fair value $ 11,650,257 $ 8,071,140
Residential Mortgage Loans Held-for-Sale, At Fair Value    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held-for-sale, fair value $ 524,862  
Residential Mortgage Loans Held-for-Sale, At Fair Value | Minimum | Discount Rate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for sale, measurement input 0.0375  
Residential Mortgage Loans Held-for-Sale, At Fair Value | Minimum | Prepayment Rate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for sale, measurement input 0.1000  
Residential Mortgage Loans Held-for-Sale, At Fair Value | Minimum | Delinquency    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for sale, measurement input 0.0000  
Residential Mortgage Loans Held-for-Sale, At Fair Value | Minimum | Loss Severity    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for sale, measurement input 0.000  
Residential Mortgage Loans Held-for-Sale, At Fair Value | Maximum | Discount Rate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for sale, measurement input 0.0400  
Residential Mortgage Loans Held-for-Sale, At Fair Value | Maximum | Prepayment Rate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for sale, measurement input 0.1500  
Residential Mortgage Loans Held-for-Sale, At Fair Value | Maximum | Delinquency    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for sale, measurement input 0.040  
Residential Mortgage Loans Held-for-Sale, At Fair Value | Maximum | Loss Severity    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for sale, measurement input 0.500  
Residential Mortgage Loans, Held-for-Investment, at Fair Value    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans, held-for-investment, fair value $ 123,606  
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Discount Rate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for investment, measurement input 0.0400  
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Prepayment Rate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for investment, measurement input 0.100  
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Delinquency    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for investment, measurement input 0.002  
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Loss Severity    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Loans held for investment, measurement input 0.200  
IRLCs    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Derivative, fair value disclosure $ 8,357  
IRLCs | Minimum | Loan Funding Probability    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Derivative, measurement input 0.4600  
IRLCs | Minimum | Fair Value of Initial Servicing Rights    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Derivative, measurement input 0  
IRLCs | Maximum | Loan Funding Probability    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Derivative, measurement input 1.0000  
IRLCs | Maximum | Fair Value of Initial Servicing Rights    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Derivative, measurement input 0.0326  
Mortgage-Backed Securities Issued    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 117,470  
Mortgage-Backed Securities Issued | Loss Severity    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities, measurement input 0.100  
Mortgage-Backed Securities Issued | Minimum | Discount Rate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities, measurement input 0.0350  
Mortgage-Backed Securities Issued | Minimum | Prepayment Rate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities, measurement input 0.090  
Mortgage-Backed Securities Issued | Minimum | Delinquency    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities, measurement input 0.0000  
Mortgage-Backed Securities Issued | Maximum | Discount Rate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities, measurement input 0.0525  
Mortgage-Backed Securities Issued | Maximum | Prepayment Rate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities, measurement input 0.120  
Mortgage-Backed Securities Issued | Maximum | Delinquency    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities, measurement input 0.0025