Reserve for loans impairments recorded after acquisition as a result of current information and events which result in it being probable that estimated cash flows will be less than previously expected or because actual cash flows are less than cash flows previously expected. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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LOAN PORTFOLIO- Carrying Value of Purchased Credit Impaired Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable Impaired [Line Items]
Loans and Leases Receivable, Gross	$ 8,996,816	$ 8,858,123	$ 8,695,890
Residential Portfolio Segment [Member]
Financing Receivable Impaired [Line Items]
Loans and Leases Receivable, Gross	3,126,562	3,163,208	3,267,868
Commercial Portfolio Segment [Member]
Financing Receivable Impaired [Line Items]
Loans and Leases Receivable, Gross	3,854,962	3,750,202
Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member]
Financing Receivable Impaired [Line Items]
Loans and Leases Receivable, Gross	1,558,724	1,522,662	1,552,503
PCI loans
Financing Receivable Impaired [Line Items]
Loans and Leases Receivable, Gross	144,443	146,640	155,281	$ 158,174
Allowance for loan losses Purchased Credit Impaired	(11,354)	(11,354)	(11,251)	$ (11,251)
Purchased Credit Impaired Loans, Net	133,089	135,286	144,030
PCI loans \| Residential Portfolio Segment [Member]
Financing Receivable Impaired [Line Items]
Loans and Leases Receivable, Gross	140,979	143,176	151,067
Allowance for loan losses Purchased Credit Impaired	(10,954)	(10,954)	(10,873)
PCI loans \| Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member]
Financing Receivable Impaired [Line Items]
Loans and Leases Receivable, Gross	3,464	3,464	4,214
Allowance for loan losses Purchased Credit Impaired	$ (400)	$ (400)	$ (378)