Fair Value - Summary of Assets and Liabilities in Each Level of Fair Value Hierarchy (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Assets
Assets, Fair Value	$ 10,184,477,000	$ 6,710,211,000
Assets, Fair Value	50,890,000	53,975,000
Assets, Fair Value	880,950,000	0
Assets, Fair Value	229,383,000	949,000
Liabilities
Liabilities, Fair Value	85,723,000	25,348,000
Liabilities, Fair Value	721,080,000	757,286,000
Liabilities, Fair Value	7,805,846,000	5,874,552,000
Mandatory Repurchase Obligation [Member]
Liabilities
Liabilities, Fair Value	8,867,000	9,999,000
Professional Fees Liability Related to Certain Securitizations [Member]
Liabilities
Liabilities, Fair Value	7,350,000	8,147,000
Contingent Earn-Out Payments [Member]
Liabilities
Liabilities, Fair Value	10,900,000	6,100,000
Mortgage-Backed Debt Related to Non-Residual Trusts [Member]
Liabilities
Liabilities, Fair Value	721,080,000	757,286,000
HMBS Related Obligations [Member]
Liabilities
Liabilities, Fair Value	7,805,846,000	5,874,552,000
Liability [Member]
Liabilities
Liabilities, Fair Value	8,612,649,000	6,657,186,000
Derivative Financial Instruments, Assets [Member]
Assets
Assets, Fair Value	229,383,000	949,000
Derivative Financial Instruments, Liabilities [Member]
Liabilities
Liabilities, Fair Value	58,606,000	1,102,000
Reverse Mortgage Loans [Member]
Assets
Assets, Fair Value	7,906,635,000	6,047,108,000
Residential Loans Related to Non-Residual Trusts [Member]
Assets
Assets, Fair Value	613,627,000	646,498,000
Forward Loans Held for Sale [Member]
Assets
Assets, Fair Value	1,664,215,000	16,605,000
Receivables Related to Non-Residual Trusts [Member]
Assets
Assets, Fair Value	50,890,000	53,975,000
Servicing Rights Carried at Fair Value [Member]
Assets
Assets, Fair Value	880,950,000
Assets [Member]
Assets
Assets, Fair Value	11,345,700,000	6,765,135,000
Level 1 [Member] \| Mandatory Repurchase Obligation [Member]
Liabilities
Liabilities, Fair Value
Level 1 [Member] \| Professional Fees Liability Related to Certain Securitizations [Member]
Liabilities
Liabilities, Fair Value
Level 1 [Member] \| Contingent Earn-Out Payments [Member]
Liabilities
Liabilities, Fair Value
Level 1 [Member] \| Mortgage-Backed Debt Related to Non-Residual Trusts [Member]
Liabilities
Liabilities, Fair Value
Level 1 [Member] \| HMBS Related Obligations [Member]
Liabilities
Liabilities, Fair Value
Level 1 [Member] \| Liability [Member]
Liabilities
Liabilities, Fair Value
Level 1 [Member] \| Derivative Financial Instruments, Assets [Member]
Assets
Assets, Fair Value
Level 1 [Member] \| Derivative Financial Instruments, Liabilities [Member]
Liabilities
Liabilities, Fair Value
Level 1 [Member] \| Reverse Mortgage Loans [Member]
Assets
Assets, Fair Value
Level 1 [Member] \| Residential Loans Related to Non-Residual Trusts [Member]
Assets
Assets, Fair Value
Level 1 [Member] \| Forward Loans Held for Sale [Member]
Assets
Assets, Fair Value
Level 1 [Member] \| Receivables Related to Non-Residual Trusts [Member]
Assets
Assets, Fair Value
Level 1 [Member] \| Assets [Member]
Assets
Assets, Fair Value
Level 2 [Member] \| Liability [Member]
Liabilities
Liabilities, Fair Value	39,279,000	1,102,000
Level 2 [Member] \| Derivative Financial Instruments, Assets [Member]
Assets
Assets, Fair Value	167,703,000
Level 2 [Member] \| Derivative Financial Instruments, Liabilities [Member]
Liabilities
Liabilities, Fair Value	39,279,000	1,102,000
Level 2 [Member] \| Forward Loans Held for Sale [Member]
Assets
Assets, Fair Value	1,664,215,000	16,605,000
Level 2 [Member] \| Assets [Member]
Assets
Assets, Fair Value	1,831,918,000	16,605,000
Level 3 [Member] \| Mandatory Repurchase Obligation [Member]
Liabilities
Liabilities, Fair Value	8,867,000	9,999,000
Level 3 [Member] \| Professional Fees Liability Related to Certain Securitizations [Member]
Liabilities
Liabilities, Fair Value	7,350,000	8,147,000
Level 3 [Member] \| Contingent Earn-Out Payments [Member]
Liabilities
Liabilities, Fair Value	10,900,000	6,100,000
Level 3 [Member] \| Mortgage-Backed Debt Related to Non-Residual Trusts [Member]
Liabilities
Liabilities, Fair Value	721,080,000	757,286,000
Level 3 [Member] \| HMBS Related Obligations [Member]
Liabilities
Liabilities, Fair Value	7,805,846,000	5,874,552,000
Level 3 [Member] \| Liability [Member]
Liabilities
Liabilities, Fair Value	8,573,370,000	6,656,084,000
Level 3 [Member] \| Derivative Financial Instruments, Assets [Member]
Assets
Assets, Fair Value	61,680,000	949,000
Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member]
Liabilities
Liabilities, Fair Value	19,327,000
Level 3 [Member] \| Reverse Mortgage Loans [Member]
Assets
Assets, Fair Value	7,906,635,000	6,047,108,000
Level 3 [Member] \| Residential Loans Related to Non-Residual Trusts [Member]
Assets
Assets, Fair Value	613,627,000	646,498,000
Level 3 [Member] \| Receivables Related to Non-Residual Trusts [Member]
Assets
Assets, Fair Value	50,890,000	53,975,000
Level 3 [Member] \| Servicing Rights Carried at Fair Value [Member]
Assets
Assets, Fair Value	880,950,000
Level 3 [Member] \| Assets [Member]
Assets
Assets, Fair Value	$ 9,513,782,000	$ 6,748,530,000

Fair value portion of amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 14

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 3

-Subparagraph a, b

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- Definition

Fair value portion of accrued expenses.

+ References

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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- Definition

Fair value of financial and nonfinancial obligations.

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- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

+ References

No definition available.

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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Glossary Loan

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- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 50

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

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- Definition

Beneficial interest at fair value.

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No definition available.

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- Definition

Home equity conversion mortgage backed security related obligations.

+ References

No definition available.

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