SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Mortgage Banking and Guaranty Obligations (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Mortgage Banking Activities
Co-broker fees	$ 20.6	$ 22.8	$ 19.3
Fair value of expected guaranty obligation recognized at commitment	$ 16.3	$ 16.0	$ 13.8
Fannie Mae DUS program \| Maximum
Guaranty Obligation and Allowance for Credit Losses
Maximum delinquency period of loans at which initial loss recognition occurs	60 days
MSRs \| Minimum
Mortgage Banking Activities
Discount rate used for estimated capitalized MSRs (as a percent)	10.00%	10.00%	10.00%
Reduction in estimated life of MSRs	6 months
MSRs \| Maximum
Mortgage Banking Activities
Discount rate used for estimated capitalized MSRs (as a percent)	15.00%	15.00%	15.00%
Reduction in estimated life of MSRs	12 months

Discount rate which is used to value residual cash flows generated by financial assets of the securitization, asset-backed financing arrangement, or similar transfer for initial fair value measurement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118948506&loc=d3e107207-111719

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- References

No definition available.

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- References

No definition available.

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- Definition

The amount of expense during the period for co-broker fees paid for obtaining loans.

+ References

No definition available.

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- Definition

Decrease in gains from mortgage banking gains due to the recognition at commitment of the fair value of expected guaranty obligations.

+ References

No definition available.

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- Definition

Maximum number of days a loan is delinquent before a loss is typically recognized in the financial statements.

+ References

No definition available.

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- Definition

Represents the reduction in estimated life of financial assets and financial liabilities based upon the expiration of various types of prepayment penalty and/or lockout provisions prior to that stated maturity date.

+ References

No definition available.

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