Loans, Loans Held For Sale, Notes and Certificates and Loan Servicing Rights (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	$ 3,413,893	$ 4,311,984
Loans held for sale	265,925	9,048
Fair Value	3,515,578	4,320,895
Fair Value, Measurements, Recurring \| Loans(1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Aggregate principal balance outstanding	3,620,061	4,565,653
Fair value adjustments	(206,168)	(253,669)
Loans	3,413,893	4,311,984
Fair Value, Measurements, Recurring \| Loans Held For Sale(1)(2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Aggregate principal balance outstanding	277,191	9,345
Fair value adjustments	(11,266)	(297)
Loans held for sale	265,925	9,048
Fair Value, Measurements, Recurring \| Notes and Certificates
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Aggregate principal balance outstanding	3,725,615	4,572,912
Fair value adjustments	(210,037)	(252,017)
Fair Value	3,515,578	4,320,895
Fair Value, Measurements, Recurring \| Loans Held for Sale Related to LCAM Legacy Fund Wind-down
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale	91,533	0
Loans Invested in by Company \| Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Aggregate principal balance outstanding	194,190	27,860
Fair value adjustments	(7,396)	(1,949)
Loans and loans held for sale	186,794	25,911
Loans Invested in by Company \| Fair Value, Measurements, Recurring \| Loans(1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Aggregate principal balance outstanding	13,891	18,515
Fair value adjustments	(1,488)	(1,652)
Loans	12,403	16,863
Loans Invested in by Company \| Fair Value, Measurements, Recurring \| Loans Held For Sale(1)(2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Aggregate principal balance outstanding	180,299	9,345
Fair value adjustments	(5,908)	(297)
Loans held for sale	$ 174,391	$ 9,048

Loans Receivable and Loans Held for Sale, Fair Value Disclosure

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Notes and Certificates at fair value

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- Definition

Principal amount of loan before fair value adjustment.

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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.

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- Definition

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

+ References

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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
-URI http://asc.fasb.org/subtopic&trid=2196772

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