Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended						6 Months Ended				6 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013 Additional Borrowing Capacity Floating Rate Reverse Mortgage Loans [Member]	Jun. 30, 2013 Additional Borrowing Capacity Fixed Rate Reverse Mortgage Loans [Member]	Jun. 30, 2013 Commitment to Lend [Member]	Jun. 30, 2013 Commitment to Purchase Loans [Member]	Jun. 30, 2013 Commitment to Sell [Member]	Jun. 30, 2013 Obligation to Repurchase Receivables Sold [Member]	Jun. 30, 2013 Representations and Warranties [Member]	Jun. 30, 2013 Professional Fees Liability [Member]	Jun. 30, 2013 Curtailment Obligation Liability [Member]	Jun. 30, 2013 VIE [Member] Trust	Dec. 31, 2012 VIE [Member]	Jun. 30, 2013 VIE Primary Beneficiary [Member] Non-Residual Trusts [Member] Trust
Loss Contingencies [Line Items]
Mandatory repurchase obligation delinquency threshold								90 days
Outstanding loans associated with mandatory repurchase obligation								$ 81,300,000
Mandatory repurchase obligation								8,900,000	2,200,000	7,400,000
Estimated gross amount of payments relating to professional fees liability								11,100,000		9,900,000
Reimbursement obligation of LOC, if drawn												165,000,000
Number of Non-Residual Trusts with reimbursement obligations consolidated on balance sheet														7
Aggregate number of securitization trusts consolidated and not consolidated with reimbursement obligations												11
Amount of LOCs available for eleven securitization trusts												280,800,000	285,400,000
Outstanding balance of collateral for mandatory clean-up call obligation	418,300,000	418,300,000												418,300,000
Expected period to exercise mandatory clean-up call obligation														2017 and continuing through 2019
Additional borrowing capacity available to borrowers			306,700,000	4,200,000	4,300,000,000		7,500,000,000
Commitments to purchase loans						2,200,000,000
Curtailment obligation liability	44,800,000	44,800,000									44,800,000
Possible losses in excess of recorded liability											14,100,000
Liability assumed	38,800,000	38,800,000
Provision in general and administrative expenses	$ 6,000,000	$ 6,000,000