Expected Loss to be Paid - Key Assumptions in Base Case Expected Loss Second Lien RMBS (Details)		3 Months Ended	6 Months Ended	12 Months Ended
		Mar. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Expected period until final CDR	[1]	34 months	34 months	34 months
RMBS [Member] | United States [Member] | HELOCs [Member] | Minimum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	[1]	2.30%	5.30%	2.80%
Final CDR	[1]	0.50%	0.50%	0.50%
Initial CPR	[1]	6.90%	9.30%	6.90%
Final CPR	[1],[2]	10.00%	10.00%	15.00%
Loss severity	[1]	90.00%	90.00%	90.00%
RMBS [Member] | United States [Member] | HELOCs [Member] | Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	[1]	7.50%	23.30%	6.80%
Final CDR	[1]	3.20%	3.20%	3.20%
Initial CPR	[1]	23.20%		21.80%
Final CPR	[1],[2]	23.20%	15.00%	21.80%
Loss severity	[1]	98.00%	98.00%	98.00%
RMBS [Member] | United States [Member] | HELOCs [Member] | Weighted Average [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	[1]	4.40%	8.90%	4.10%
Final CDR	[1]	1.20%	1.20%	1.20%
Initial CPR	[1]	10.20%	9.30%	11.00%
Final CPR	[1],[2]	15.20%	13.25%	15.50%
Loss severity	[1]	90.40%	90.50%	90.40%
RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Expected period until final CDR	[1]	34 months	34 months	34 months
Final CPR	[1],[2]	15.00%	15.00%	15.00%
Loss severity	[1]	98.00%	98.00%	98.00%
RMBS [Member] | United States [Member] | Closed-end [Member] | Minimum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	[1]	4.70%	6.00%	5.50%
Final CDR	[1]	3.50%	3.50%	3.50%
Initial CPR	[1]	3.40%	5.30%	2.80%
RMBS [Member] | United States [Member] | Closed-end [Member] | Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	[1]	12.40%	21.40%	12.50%
Final CDR	[1]	9.10%	9.20%	9.10%
Initial CPR	[1]	11.80%	13.40%	13.90%
RMBS [Member] | United States [Member] | Closed-end [Member] | Weighted Average [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	[1]	6.90%	10.80%	7.20%
Final CDR	[1]	4.90%	4.80%	4.90%
Initial CPR	[1]	7.60%	8.60%	9.90%
Financing Receivable, Modified in Previous 12 Months [Member] | Alt-A and Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate		25.00%	25.00%	25.00%

[1] Represents variables for most heavily weighted scenario (the “base case”).

[2] For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used.