Servicing of Residential Loans - Schedule of Total Servicing Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014 Account	Dec. 31, 2013 Account
Servicing Portfolio [Line Items]
Servicing Portfolio, Number of Accounts	2,309,648	2,051,796
Residential Loans of Securitization Trusts, Principal Balance	$ 256,112,142	$ 217,961,136
Third Party Credit Owners [Member]
Servicing Portfolio [Line Items]
Servicing Portfolio, Number of Accounts	2,192,885	1,939,109
Residential Loans of Securitization Trusts, Principal Balance	243,532,675	206,518,774
Third Party Credit Owners [Member] | Capitalized Servicing Rights [Member]
Servicing Portfolio [Line Items]
Servicing Portfolio, Number of Accounts	1,573,867	1,310,357
Residential Loans of Securitization Trusts, Principal Balance	182,207,043	146,143,213
Third Party Credit Owners [Member] | Capitalized Sub-servicing [Member]
Servicing Portfolio [Line Items]
Servicing Portfolio, Number of Accounts	187,747	235,112
Residential Loans of Securitization Trusts, Principal Balance	10,443,480	13,369,236
Third Party Credit Owners [Member] | Sub-servicing [Member]
Servicing Portfolio [Line Items]
Servicing Portfolio, Number of Accounts	431,271	393,640
Residential Loans of Securitization Trusts, Principal Balance	50,882,152	47,006,325
On-balance Sheet [Member] | Residential Loans and Real Estate Owned [Member]
Servicing Portfolio [Line Items]
Servicing Portfolio, Number of Accounts	116,763	112,687
Residential Loans of Securitization Trusts, Principal Balance	$ 12,579,467	$ 11,442,362