Securities - Debt Securities Held to Maturity by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Investments Debt And Equity Securities [Abstract]
Due in one year or less, amortized cost	$ 4,300
Due after five years through ten years, amortized cost	4,268
Due after ten years, amortized cost	4,992
Mortgage-backed GSE securities: residential, amortized cost	89,642
Held to maturity securities, Total amortized cost	103,202	$ 110,699
Due in one year or less, fair value	4,318
Due after five years through ten years, fair value	4,429
Due after ten years, fair value	5,174
Mortgage-backed GSE securities: residential, fair value	91,288
Held to maturity securities, Total fair value	$ 105,209	$ 109,644

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
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Fair value of held-to-maturity debt securities maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, maturing in the fifth through tenth fiscal year following the latest fiscal year.

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Fair value of held-to-maturity debt securities maturing after the tenth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, maturing after the tenth fiscal year following the latest fiscal year.

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-Publisher FASB
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Fair value of held-to-maturity debt securities maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of held-to-maturity debt securities at fair value that do not have a single maturity date and which the entity has decided to disclose separately rather than allocating the fair value over several maturity groupings.

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Fair value of investments in debt securities classified as held-to-maturity.

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