Loans, Notes and Certificates, and Loan Servicing Rights (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 3,230,661	$ 2,798,505
Fair Value	3,249,346	2,813,618
Interest rate, minimum	5.79%	5.79%
Interest rate, maximum	29.90%	29.90%
Fair Value, Measurements, Recurring \| Loans at Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Aggregate principal balance outstanding	3,276,356	2,836,729
Fair value adjustments	(45,695)	(38,224)
Fair Value	3,230,661	2,798,505
Fair Value, Measurements, Recurring \| Notes And Certificates At Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Aggregate principal balance outstanding	3,295,034	2,851,837
Fair value adjustments	(45,688)	(38,219)
Fair Value	$ 3,249,346	$ 2,813,618
Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes and certificates term	12 months	12 months
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes and certificates term	60 months	60 months

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- Definition

Notes and Certificates at fair value

+ References

No definition available.

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- Definition

Principal amount of loan before fair value adjustment.

+ References

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- Definition

Principal Amount Of Notes And Certificates Before Fair Value Adjustment

+ References

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- Definition

Amount of addition (reduction) to the amount at which an asset could be incurred (settled) in a current transaction between willing parties.

+ References

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- Definition

When presenting a range of interest rates, the highest effective rate for funds borrowed under the debt agreement as of the balance sheet date.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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When presenting a range of interest rates, the lowest effective rate for funds borrowed under the debt agreement as of the balance sheet date.

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Amount of addition (reduction) to the amount at which a liability could be incurred (settled) in a current transaction between willing parties.

+ 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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Glossary Loan

-URI http://asc.fasb.org/extlink&oid=6517073

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