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.

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Percentage discount rate used to calculate present value of an expected stream of future payments, which is included in the calculation of the amount of the specified guaranteed benefit obligation as of the balance sheet date.

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Estimated average rate of return on investments which is included in the calculation of the amount of the specified guaranteed benefit obligation as of the balance sheet date.

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

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

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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.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Mortgage Banking and Guaranty Obligations (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Gains from Mortgage Banking Activities
Co-broker fees from mortgage banking activities	$ 35.8	$ 18.0	$ 15.9
Fannie Mae DUS program \| Minimum
Guaranty Obligation and Allowance for Credit Losses
Average expected cash flows (as a percent)	0.03%
Discount rate (as a percent)	12.00%
Fannie Mae DUS program \| Maximum
Guaranty Obligation and Allowance for Credit Losses
Average expected cash flows (as a percent)	0.05%
Discount rate (as a percent)	15.00%
Maximum delinquency period of loans at which initial loss recognition occurs	60 days
MSRs \| Minimum
Gains from 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
Gains from 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