Residential Loans - Additional Information (Detail) (USD $)			3 Months Ended	9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended										9 Months Ended		9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Mar. 31, 2012 Sequoia Entity	Sep. 30, 2012 Sequoia Entity	Dec. 31, 2011 Sequoia	Sep. 30, 2012 Residential Loans	Sep. 30, 2011 Residential Loans	Sep. 30, 2012 Residential Loans	Sep. 30, 2011 Residential Loans	Sep. 30, 2012 Residential Loans at Fair Value	Sep. 30, 2012 Residential Loans at Fair Value Contract	Sep. 30, 2012 Residential Loans Held For Sale	Sep. 30, 2011 Residential Loans Held For Sale	Sep. 30, 2012 Residential Loans Held For Sale Contract	Sep. 30, 2011 Residential Loans Held For Sale	Dec. 31, 2011 Residential Loans Held For Sale	Sep. 30, 2012 Residential Loans Held for Investment CreditScore	Mar. 31, 2012 Residential Loans Held for Investment	Dec. 31, 2011 Residential Loans Held for Investment	Sep. 30, 2012 Residential Loans Held for Investment First Mortgage	Sep. 30, 2012 Residential Loans Held for Investment Second Mortgage	Sep. 30, 2012 Residential Loans Held for Investment Sequoia	Dec. 31, 2011 Residential Loans Held for Investment Sequoia	Sep. 30, 2012 Residential Loans Held for Investment Residential Loans Acquired Prior To July 1st 2004	Dec. 31, 2011 Residential Loans Held for Investment Residential Loans Acquired Prior To July 1st 2004	Sep. 30, 2012 Residential Loans Held for Investment Residential Loans Acquired After July 1st 2004	Dec. 31, 2011 Residential Loans Held for Investment Residential Loans Acquired After July 1st 2004
Mortgage Loans on Real Estate [Line Items]
Amount paid to purchase residential loans						$ 519,000,000		$ 1,510,000,000
Principal value of residential loan purchased for which rights to service was acquired						299,000,000		299,000,000
Number of loans											429			59
Principal value										354,000,000	354,000,000	49,000,000		49,000,000		395,000,000	3,099,411,000		3,829,847,000					1,100,000,000	1,500,000,000	2,000,000,000	2,300,000,000
Carrying value	3,494,562,000	4,194,885,000		3,076,580,000	3,799,648,000					370,000,000	370,000,000						3,076,580,000		3,799,648,000			3,076,580,000	3,799,648,000
Valuation adjustments										15,000,000		(367,000)	363,000	131,000	374,000
Residential loans												47,947,000		47,947,000		395,237,000
Unamortized premium, net																	30,917,000		36,682,000					19,000,000	23,000,000	12,000,000	14,000,000
Percentage of loans prepaid																								6.00%		15.00%
Percentage of premiums amortized																								12.00%		11.00%
Derecognized loan principal value																		308,000,000
Derecognized loan unamortized premium																		1,000,000
Number of deconsolidated securitization entities			5	5
Percentage of loan portfolio																				98.00%	2.00%
Weighted average original loan-to-value (LTV)																	66.00%
Weighted average original Fair Isaac Corporation (FICO) score																	736
Charge-offs, net						2,514,000	2,287,000	7,653,000	6,802,000
Principal value						7,000,000	8,000,000	21,000,000	23,000,000
Loss confirmation period								23 months
Average recorded investment of loans individually evaluated for impairment						16,000,000	11,000,000	15,000,000	12,000,000
Interest income recognized on impaired loans						$ 22,000	$ 168,000	$ 281,000	$ 337,000