Servicing of Residential Loans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified					3 Months Ended
	Jun. 30, 2013 Forward Loans [Member] Servicing Rights Carried at Amortized Cost [Member]	Dec. 31, 2012 Forward Loans [Member] Servicing Rights Carried at Amortized Cost [Member]	Jun. 30, 2013 Reverse Loans [Member] Servicing Rights Carried at Amortized Cost [Member]	Dec. 31, 2012 Reverse Loans [Member] Servicing Rights Carried at Amortized Cost [Member]	Jun. 30, 2013 Minimum [Member]	Jun. 30, 2013 Maximum [Member]
Servicing Assets at Fair Value [Line Items]
Fair value of servicing rights	$ 203.7	$ 229.9	$ 14.2	$ 15.7
Adverse Change in assumptions percent					10.00%	20.00%