Regulatory Restrictions - Schedule of Capital Ratios (Parenthetical) (Detail) - Basel III Capital Rules [Member]	12 Months Ended
Dec. 31, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital conservation buffer	2.50%
Capital conservation buffer	2.50%
Capital conservation buffer	2.50%
Minimum [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital to risk-weighted assets Actual, Ratio	8.00%
Common equity Tier 1 capital to risk-weighted assets Actual, Ratio	4.50%
Tier 1 capital to risk-weighted assets Actual, Ratio	6.00%
Tier 1 capital to average assets Fully Phased-In Regulatory Guidelines Minimum, Ratio	4.00%

Capital conservation buffer rate.

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- Definition

Common equity tier one capital to risk weighted assets.

+ References

No definition available.

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- Definition

Total Capital divided by risk weighted assets as defined in the regulations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1H
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826

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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.

+ References

No definition available.

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- Definition

The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1H
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958570-112826

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- Definition

Tier 1 capital divided by risk weighted assets as defined by regulations.

+ References

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