Residential Loans - Residential loans at fair value (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential loans at fair value	$ 10,184,477,000	$ 6,710,211,000
Reverse Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential loans at fair value	7,906,635,000	6,047,108,000
Residential Loans Related to Non-Residual Trusts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential loans at fair value	613,627,000	646,498,000
Residential Loans Held for Sale [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential loans at fair value	$ 1,664,215,000	$ 16,605,000