MORTGAGE SERVICING RIGHTS - Schedule of Activity Related to Capitalized MSRs (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Mortgage Servicing Rights
Beginning balance			$ 521,930
Ending balance	$ 587,909		587,909
Purchase of mortgage servicing rights				$ 42,705
MSRs
Mortgage Servicing Rights
Beginning balance	573,159	$ 468,093	521,930	412,348
Additions, following the sale of loan	48,174	60,955	165,748	124,982
Purchases				42,705
Amortization	(30,174)	(26,074)	(88,398)	(72,030)
Pre-payments and write-offs	(3,250)	(6,296)	(11,371)	(11,327)
Ending balance	$ 587,909	$ 496,678	$ 587,909	$ 496,678

The cash outflow to obtain servicing rights, which contractually entitle the servicer to receive fees and ancillary revenues for performing billing, collection, disbursement and recordkeeping services in connection with a mortgage portfolio. Rights may be obtained via (1) acquisition or assumption of a servicing obligation that does not relate to financial assets of the servicer or its consolidated affiliates; or (2) by originating mortgage loans and then (a) transferring the loans to a Variable Interest Entity (VIE) in a transaction that meets the necessary transfer and classification requirements, or (b) transferring the loans in a transaction that meets the requirements for sale accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=7524895&loc=d3e120260-111741

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Amount of other-than-temporary impairment (OTTI) applied to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

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Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of additions from purchases, assumption or transfer to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amount of amortization of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amount of additions from purchases of new servicing assets, subsequently measured at amortized cost, from a third-party servicer.

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