Fair Value - Schedule of Significant Unobservable Inputs Used in Fair Value Measurement of Assets and Liabilities on Recurring Basis (Detail)	Dec. 31, 2018 USD ($)	Feb. 09, 2018 USD ($)	Dec. 31, 2017 USD ($)
Mortgage Loans Related To Non-Residual Trusts [Member] | Loss Severity [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.89		1
HMBS Related Obligations [Member] | Weighted-Average Remaining Life [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	3 years 5 days
Recurring Measurement Basis [Member] | Weighted-Average Remaining Life [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Rights Carried at Fair Value	2 years 1 month 6 days	2 years 5 months	2 years 4 months 24 days
Recurring Measurement Basis [Member] | Weighted-Average Remaining Life [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Rights Carried at Fair Value	7 years 6 months	7 years 6 months	7 years 1 month 6 days
Recurring Measurement Basis [Member] | Weighted-Average Remaining Life [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Rights Carried at Fair Value	5 years 4 months 24 days	5 years 11 months	5 years 7 months 6 days
Recurring Measurement Basis [Member] | Conditional Prepayment Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.0242	0.0246	0.0249
Servicing Rights Carried at Fair Value	0.0512	0.0607	0.0680
Recurring Measurement Basis [Member] | Conditional Prepayment Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.0257	0.0329	0.0301
Servicing Rights Carried at Fair Value	0.2487	0.2700	0.2585
Recurring Measurement Basis [Member] | Conditional Prepayment Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.0237	0.0302	0.0279
Servicing Rights Carried at Fair Value	0.1079	0.0970	0.1110
Recurring Measurement Basis [Member] | Conditional Default Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.0141	0.0199	0.0172
Servicing Rights Carried at Fair Value	0.0003	0.0009	0.0006
Recurring Measurement Basis [Member] | Conditional Default Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.0414	0.0532	0.0602
Servicing Rights Carried at Fair Value	0.0642	0.1022	0.0320
Recurring Measurement Basis [Member] | Conditional Default Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.0307	0.0350	0.0361
Servicing Rights Carried at Fair Value	0.0077	0.0090	0.0091
Recurring Measurement Basis [Member] | Loss Severity [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.7703	0.9486	0.8888
Recurring Measurement Basis [Member] | Loss Severity [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.9996	1.0000	1.0000
Recurring Measurement Basis [Member] | Loss Severity [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.9433	0.9889	0.9771
Recurring Measurement Basis [Member] | Discount Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.0050	0.0050	0.0050
Servicing Rights Carried at Fair Value	0.0963	0.0963	0.0991
Recurring Measurement Basis [Member] | Discount Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.0050	0.0050	0.0050
Servicing Rights Carried at Fair Value	0.1311	0.1462	0.1497
Recurring Measurement Basis [Member] | Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Receivables Related to Non-Residual Trusts	0.0050	0.0050	0.0050
Servicing Rights Carried at Fair Value	0.1078	0.1170	0.1192
Recurring Measurement Basis [Member] | Cost to Service [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Rights Carried at Fair Value	62	62	62
Recurring Measurement Basis [Member] | Cost to Service [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Rights Carried at Fair Value	1,260	1,260	1,260
Recurring Measurement Basis [Member] | Cost to Service [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing Rights Carried at Fair Value	121	137	136
Recurring Measurement Basis [Member] | Loan Funding Probability [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest Rate Lock Commitments - Asset	0.0420	0.0100	0.0100
Interest Rate Lock Commitments - Liability	0.4300	0.1419	0.3364
Recurring Measurement Basis [Member] | Loan Funding Probability [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest Rate Lock Commitments - Asset	1.0000	1.0000	1.0000
Interest Rate Lock Commitments - Liability	1.0000	1.0000	1.0000
Recurring Measurement Basis [Member] | Loan Funding Probability [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest Rate Lock Commitments - Asset	0.6944	0.6249	0.6297
Interest Rate Lock Commitments - Liability	0.8846	0.8262	0.8476
Recurring Measurement Basis [Member] | Fair Value of Initial Servicing Rights Multiple [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest Rate Lock Commitments - Asset	0.01	0.02	0.01
Interest Rate Lock Commitments - Liability	0.50	0.08	0.24
Recurring Measurement Basis [Member] | Fair Value of Initial Servicing Rights Multiple [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest Rate Lock Commitments - Asset	6.50	5.64	5.24
Interest Rate Lock Commitments - Liability	5.90	5.86	4.92
Recurring Measurement Basis [Member] | Fair Value of Initial Servicing Rights Multiple [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest Rate Lock Commitments - Asset	3.60	2.79	2.74
Interest Rate Lock Commitments - Liability	3.60	3.39	3.32
Recurring Measurement Basis [Member] | Reverse Loans [Member] | Weighted-Average Remaining Life [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0 years	3 months	3 months 18 days
Recurring Measurement Basis [Member] | Reverse Loans [Member] | Weighted-Average Remaining Life [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	9 years 5 months 6 days	10 years 2 months	10 years 2 months 12 days
Recurring Measurement Basis [Member] | Reverse Loans [Member] | Weighted-Average Remaining Life [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	2 years 9 months 18 days	3 years 6 months	3 years 9 months 18 days
Recurring Measurement Basis [Member] | Reverse Loans [Member] | Conditional Repayment Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.1271	0.1261	0.1261
Recurring Measurement Basis [Member] | Reverse Loans [Member] | Conditional Repayment Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.6589	0.7168	0.7168
Recurring Measurement Basis [Member] | Reverse Loans [Member] | Conditional Repayment Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.3225	0.3443	0.3023
Recurring Measurement Basis [Member] | Reverse Loans [Member] | Discount Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0182	0.0279	0.0305
Recurring Measurement Basis [Member] | Reverse Loans [Member] | Discount Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0436	0.0417	0.0417
Recurring Measurement Basis [Member] | Reverse Loans [Member] | Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0384	0.0359	0.0360
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Conditional Prepayment Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0209	0.0199	0.0208
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Conditional Prepayment Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0241	0.0251	0.0253
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Conditional Prepayment Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0223	0.0230	0.0234
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Conditional Default Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0121	0.0105	0.0101
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Conditional Default Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0414	0.0470	0.0497
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Conditional Default Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0206	0.0255	0.0261
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Loss Severity [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.7897	0.9630	0.9060
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Loss Severity [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.9996	1.0000	1.0000
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Loss Severity [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.9355	0.9979	0.9946
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Discount Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0832	0.0832	0.0832
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Discount Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0832	0.0832	0.0832
Recurring Measurement Basis [Member] | Mortgage Loans Related To Non-Residual Trusts [Member] | Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0832	0.0832	0.0832
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Conditional Prepayment Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.0266
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Conditional Prepayment Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.0357
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Conditional Prepayment Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.0306
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Conditional Default Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.0413
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Conditional Default Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.0532
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Conditional Default Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.0453
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Loss Severity [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.2700
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Loss Severity [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.3000
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Loss Severity [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.2825
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Discount Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.0825
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Discount Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.0825
Recurring Measurement Basis [Member] | Mortgage Loans Related To Residual Trusts and Other Loans Held for Investment [Member] | Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value		0.0825
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Conditional Prepayment Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0481	0.0481	0.0481
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Conditional Prepayment Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0481	0.0481	0.0481
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Conditional Prepayment Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0481	0.0481	0.0481
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Conditional Default Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0246	0.0246	0.0246
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Conditional Default Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0246	0.0246	0.0246
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Conditional Default Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0246	0.0246	0.0246
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Loss Severity [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.9940	0.9940	0.9940
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Loss Severity [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.9940	0.9940	0.9940
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Loss Severity [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.9940	0.9940	0.9940
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Discount Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0980	0.0980	0.0980
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Discount Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0980	0.0980	0.0980
Recurring Measurement Basis [Member] | Mortgage Loans Held for Sale [Member] | Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0980	0.0980	0.0980
Recurring Measurement Basis [Member] | Charged-off Loans [Member] | Collection Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0371	0.0342	0.0284
Recurring Measurement Basis [Member] | Charged-off Loans [Member] | Collection Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0569	0.0605	0.0447
Recurring Measurement Basis [Member] | Charged-off Loans [Member] | Collection Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.0380	0.0355	0.0292
Recurring Measurement Basis [Member] | Charged-off Loans [Member] | Discount Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.2800	0.2800	0.2800
Recurring Measurement Basis [Member] | Charged-off Loans [Member] | Discount Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.2800	0.2800	0.2800
Recurring Measurement Basis [Member] | Charged-off Loans [Member] | Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Residential Loans at Fair Value	0.2800	0.2800	0.2800
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Conditional Prepayment Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0224	0.0246	0.0249
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Conditional Prepayment Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0257	0.0329	0.0301
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Conditional Prepayment Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0237	0.0302	0.0279
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Conditional Default Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0141	0.0199	0.0172
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Conditional Default Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0414	0.0532	0.0602
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Conditional Default Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0307	0.0350	0.0361
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Loss Severity [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.7703	0.9486	0.8888
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Loss Severity [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.9996	1.0000	1.0000
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Loss Severity [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.9433	0.9889	0.9771
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Discount Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0600	0.0600	0.0600
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Discount Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0600	0.0600	0.0600
Recurring Measurement Basis [Member] | Mortgage-Backed Debt Related to Non-Residual Trusts [Member] | Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0600	0.0600	0.0600
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Conditional Prepayment Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.0266
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Conditional Prepayment Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.0357
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Conditional Prepayment Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.0306
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Conditional Default Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.0413
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Conditional Default Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.0532
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Conditional Default Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.0453
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Loss Severity [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.2700
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Loss Severity [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.3000
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Loss Severity [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.2825
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Discount Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.0600
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Discount Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.0600
Recurring Measurement Basis [Member] | Mortgage Backed Debt Related To Residual Trusts [Member] | Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt		0.0600
Recurring Measurement Basis [Member] | HMBS Related Obligations [Member] | Weighted-Average Remaining Life [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0 years	3 months 18 days	4 months 24 days
Recurring Measurement Basis [Member] | HMBS Related Obligations [Member] | Weighted-Average Remaining Life [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	7 years	7 years 8 months 12 days	7 years 9 months 18 days
Recurring Measurement Basis [Member] | HMBS Related Obligations [Member] | Weighted-Average Remaining Life [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	3 years 5 days	3 years 2 months	3 years 8 months
Recurring Measurement Basis [Member] | HMBS Related Obligations [Member] | Conditional Repayment Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.1300	0.1290	0.1290
Recurring Measurement Basis [Member] | HMBS Related Obligations [Member] | Conditional Repayment Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.7752	0.7957	0.8687
Recurring Measurement Basis [Member] | HMBS Related Obligations [Member] | Conditional Repayment Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.3460	0.3732	0.3207
Recurring Measurement Basis [Member] | HMBS Related Obligations [Member] | Discount Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0175	0.0281	0.0302
Recurring Measurement Basis [Member] | HMBS Related Obligations [Member] | Discount Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0402	0.0391	0.0398
Recurring Measurement Basis [Member] | HMBS Related Obligations [Member] | Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt	0.0364	0.0339	0.0345