Fair Value - Reconciliation of Beginning and Ending Balances of Company's Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) (Fair Value, Measurements, Recurring [Member], Level 3 [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Assets, Beginning Balance	$ 8,607,300	$ 765,748	$ 6,774,912	$ 754,496
Business Acquisition, Assets	242,604		242,604
Assets, Total Gains (Losses) Included in Net Income	186,645	18,600	324,327	68,971
Assets, Purchases	484,379		1,789,258
Assets, Sales	(272)		(76,441)
Assets, Issuances	374,277		683,758
Assets, Settlements	(138,547)	(37,559)	(224,636)	(76,678)
Fair Value Assets, Ending Balance	9,513,782	746,789	9,513,782	746,789
Fair Value Liabilities, Beginning Balance	(7,653,245)	(840,183)	(6,656,084)	(832,760)
Liabilities, Acquisition
Liabilities, Total Gains (Losses) Included in Net Income	(110,275)	(17,354)	(170,373)	(62,513)
Liabilities, Purchases
Liabilities, Sales
Liabilities, Issuances	(943,359)		(1,972,103)
Liabilities, Settlements	133,509	36,439	225,190	74,175
Fair Value Liabilities, Ending Balance	(8,573,370)	(821,098)	(8,573,370)	(821,098)
Mandatory Repurchase Obligation [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Liabilities, Beginning Balance	(9,695)	(11,573)	(9,999)	(11,849)
Liabilities, Acquisition
Liabilities, Total Gains (Losses) Included in Net Income	566	118	404	(177)
Liabilities, Purchases
Liabilities, Sales
Liabilities, Settlements	262	555	728	1,126
Fair Value Liabilities, Ending Balance	(8,867)	(10,900)	(8,867)	(10,900)
Professional Fees Liability Related to Certain Securitizations [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Liabilities, Beginning Balance	(7,739)	(9,265)	(8,147)	(9,666)
Liabilities, Acquisition
Liabilities, Total Gains (Losses) Included in Net Income	(210)	(268)	(430)	(554)
Liabilities, Purchases
Liabilities, Sales
Liabilities, Settlements	599	673	1,227	1,360
Fair Value Liabilities, Ending Balance	(7,350)	(8,860)	(7,350)	(8,860)
Contingent Earn-Out Payments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Liabilities, Beginning Balance	(9,794)		(6,100)
Liabilities, Acquisition
Liabilities, Total Gains (Losses) Included in Net Income	(1,106)		(4,800)
Liabilities, Purchases
Liabilities, Sales
Fair Value Liabilities, Ending Balance	(10,900)		(10,900)
Mortgage-Backed Debt Related to Non-Residual Trusts [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Liabilities, Beginning Balance	(738,434)	(819,345)	(757,286)	(811,245)
Liabilities, Acquisition
Liabilities, Total Gains (Losses) Included in Net Income	(15,845)	(17,204)	(29,850)	(61,782)
Liabilities, Purchases
Liabilities, Sales
Liabilities, Settlements	33,199	35,211	66,056	71,689
Fair Value Liabilities, Ending Balance	(721,080)	(801,338)	(721,080)	(801,338)
HMBS Related Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Liabilities, Beginning Balance	(6,887,583)		(5,874,552)
Liabilities, Acquisition
Liabilities, Total Gains (Losses) Included in Net Income	(74,353)		(116,370)
Liabilities, Purchases
Liabilities, Sales
Liabilities, Issuances	(943,359)		(1,972,103)
Liabilities, Settlements	99,449		157,179
Fair Value Liabilities, Ending Balance	(7,805,846)		(7,805,846)
Interest Rate Lock Commitments [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities, Acquisition
Liabilities, Total Gains (Losses) Included in Net Income	(19,327)		(19,327)
Liabilities, Purchases
Liabilities, Sales
Fair Value Liabilities, Ending Balance	(19,327)		(19,327)
Reverse Mortgage Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Assets, Beginning Balance	7,106,943		6,047,108
Assets, Total Gains (Losses) Included in Net Income	101,304		184,581
Assets, Purchases	464,494		1,258,891
Assets, Sales	(272)		(76,441)
Assets, Issuances	337,972		646,163
Assets, Settlements	(103,806)		(153,667)
Fair Value Assets, Ending Balance	7,906,635		7,906,635
Residential Loans Related to Non-Residual Trusts [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Assets, Beginning Balance	627,430	687,848	646,498	672,714
Assets, Total Gains (Losses) Included in Net Income	16,938	24,263	29,957	74,075
Assets, Settlements	(30,741)	(33,429)	(62,828)	(68,107)
Fair Value Assets, Ending Balance	613,627	678,682	613,627	678,682
Receivables Related to Non-Residual Trusts [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Assets, Beginning Balance	53,671	77,900	53,975	81,782
Assets, Total Gains (Losses) Included in Net Income	1,219	(5,663)	5,056	(5,104)
Assets, Settlements	(4,000)	(4,130)	(8,141)	(8,571)
Fair Value Assets, Ending Balance	50,890	68,107	50,890	68,107
Servicing Rights Carried at Fair Value [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Assets, Beginning Balance	759,683		26,382
Business Acquisition, Assets	242,604		242,604
Assets, Total Gains (Losses) Included in Net Income	65,077		44,002
Assets, Purchases	19,885		530,367
Assets, Issuances	36,305		37,595
Fair Value Assets, Ending Balance	880,950		880,950
Derivative Financial Instruments, Assets [Member] | Interest Rate Lock Commitments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value Assets, Beginning Balance	59,573		949
Assets, Total Gains (Losses) Included in Net Income	2,107		60,731
Fair Value Assets, Ending Balance	$ 61,680		$ 61,680