Servicing of Residential Loans - Schedule of Total Servicing Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013 Accounts	Dec. 31, 2012 Accounts
Servicing Portfolio [Line Items]
Total servicing portfolio, Number of Accounts	1,960,270	1,038,981
Total servicing portfolio, Unpaid Principal Balance	$ 211,226,362	$ 90,094,189
Third-party investors [Member]
Servicing Portfolio [Line Items]
Total servicing portfolio, Number of Accounts	1,848,981	945,260
Total servicing portfolio, Unpaid Principal Balance	200,026,907	82,113,522
Third-party investors [Member] | Capitalized Servicing Rights [Member]
Servicing Portfolio [Line Items]
Total servicing portfolio, Number of Accounts	1,319,063	415,617
Total servicing portfolio, Unpaid Principal Balance	140,566,180	23,469,620
Third-party investors [Member] | Capitalized sub-servicing [Member]
Servicing Portfolio [Line Items]
Total servicing portfolio, Number of Accounts	266,852	289,417
Total servicing portfolio, Unpaid Principal Balance	14,832,510	16,333,529
Third-party investors [Member] | Sub-servicing [Member]
Servicing Portfolio [Line Items]
Total servicing portfolio, Number of Accounts	263,066	240,226
Total servicing portfolio, Unpaid Principal Balance	44,628,217	42,310,373
On-balance sheet [Member]
Servicing Portfolio [Line Items]
Total servicing portfolio, Number of Accounts	111,289	93,721
Total servicing portfolio, Unpaid Principal Balance	11,199,455	7,980,667
On-balance sheet [Member] | Residential loans and real estate owned [Member]
Servicing Portfolio [Line Items]
Total servicing portfolio, Number of Accounts	111,289	93,721
Total servicing portfolio, Unpaid Principal Balance	$ 11,199,455	$ 7,980,667