Available-for-sale, securities in unrealized loss, percentage.

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Excess present value of future cash flows over our current book value.

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- Definition

Excess subordination as a percentage of current performing collateral.

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No definition available.

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- Definition

Fair Value Inputs, Collateral

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No definition available.

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- Definition

Fair Value Inputs, Coupon Rate

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No definition available.

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- Definition

Fair Value Inputs , Prepayment Rate After Year Two

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- Definition

Fair Value Inputs , Prepayment Rate Year One and Two

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- Definition

Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss

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No definition available.

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- Definition

Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total

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No definition available.

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- Definition

Number of banks and other financial institutions comprising the security.

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No definition available.

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Number Of Pooled Securities with No Senior Class

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No definition available.

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- Definition

Number of Securities with Excess Subordination

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No definition available.

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Number of Securities with No Excess Subordination

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- Definition

Percent of Unrealized Losses

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No definition available.

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- Definition

Percentage of principal amount in pooled security securities.

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No definition available.

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- Definition

Probabilities for performing collateral range.

+ References

No definition available.

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- Definition

Probability of default.

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No definition available.

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- Definition

Probability percentage assigned to default bank.

+ References

No definition available.

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- Definition

Probability percentage assigned to default bank subject to market indicators.

+ References

No definition available.

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- Definition

Projected recovery rate.

+ References

No definition available.

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- Definition

Subordinated tranches range.

+ References

No definition available.

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563

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- Definition

Rate at which loans or a loan portfolio are expected to prepay principal balances, used as an input to measure fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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- Definition

Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 325
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6478792&loc=d3e63345-112809

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- Definition

The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 8B
-URI http://asc.fasb.org/extlink&oid=73527792&loc=SL6284393-111563

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Impairment of Investment Securities - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) Security Bank	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Security Bank	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other than temporary impairment charges recognized			$ 0	$ 0
Amortized Cost	$ 784,875,000		784,875,000		$ 790,082,000
Securities available for sale, at fair value	778,644,000		778,644,000		778,612,000
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 15,251,000		$ 15,251,000		22,501,000
Number of banks and other financial institutions comprising the security \| Bank	250		250
Number Of Pooled Securities with No Senior Class \| Security			2
Number of securities with no excess subordination \| Security	2		2
Number of Securities with Excess Subordination \| Security	6		6
Coupon rate			7.00%
Probability of default			100.00%
Projected recovery rate			0.00%
Probability percentage assigned to default bank subject to market indicators			10.00%
Probability percentage assigned to default bank			100.00%
Federal Home Loan Bank Stock	$ 32,302,000		$ 32,302,000		36,498,000
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total	73		73
Minimum [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Subordinated tranches range	7.00%		7.00%
Total principal amount of the respective securities	5.00%		5.00%
Excess subordination as a percentage of current performing collateral			2.00%
Probabilities for performing collateral range			0.33%
Excess present value of future cash flows over our current book value			18.00%
Maximum [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Subordinated tranches range	35.00%		35.00%
Excess subordination as a percentage of current performing collateral			65.00%
Probabilities for performing collateral range			75.00%
Excess present value of future cash flows over our current book value			108.00%
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Percent of Unrealized Losses	42.00%		42.00%
Securities available for sale, at fair value	$ 34,629,000		$ 34,629,000		33,292,000
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 6,481,000		6,481,000		7,124,000
Trust preferred collateralized debt obligations [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other than temporary impairment charges recognized			$ 0	$ 0
Percentage of Current Performing Collateral	0.00%		0.00%
Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Securities available for sale, at fair value	$ 16,578,000		$ 16,578,000		6,319,000
Pooled Trust Preferred Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other than temporary impairment charges recognized	0	$ 0
Equity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other than temporary impairment charges recognized	0	$ 0
Continuous Unrealized Loss Position, Fair Value	0		0		0
Asset Size and Coupon Rate 1 [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Collateral issued by financial institutions	15,000,000,000		$ 15,000,000,000
Coupon rate			7.00%
Prepayment rate			100.00%
Asset Size and Coupon Rate 2 [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Coupon rate			7.00%
Fair Value Inputs , Prepayment Rate Year One and Two			40.00%
Fair Value Inputs , Prepayment Rate After Year Two			2.00%
Asset Size and Coupon Rate 3 [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Prepayment rate			5.00%
Asset Size and Coupon Rate 3 [Member] \| Minimum [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Collateral issued by financial institutions	2,000,000,000		$ 2,000,000,000
Asset Size and Coupon Rate 3 [Member] \| Maximum [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Collateral issued by financial institutions	15,000,000,000		15,000,000,000
Asset Size and Coupon Rate 4 [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Collateral issued by financial institutions	$ 2,000,000,000		$ 2,000,000,000
Coupon rate			10.00%
Prepayment rate			5.00%
Asset Size and Coupon Rate 5 [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Prepayment rate			0.00%
Obligations of U.S. Government-Sponsored Enterprises - Other Government-Sponsored Enterprises [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Percent of Unrealized Losses	50.00%		50.00%
Reported Value Measurement [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Securities available for sale, at fair value	$ 778,644,000		$ 778,644,000		$ 778,612,000
Federal Home Loan Bank Stock	$ 32,302,000		$ 32,302,000