Qualified Affordable Housing Projects and Other Tax Credit Investments - Schedule of Qualified Affordable Housing Projects and Other Tax Credit Investments (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Investment Holdings [Line Items]
Total	$ 39,327		$ 35,048
Total	23,802		20,816
Amortization Expense	941	$ 201
Tax Benefit Recognized	(2,817)	(281)
LIHTC and Other Qualifying Investments [Member]
Investment Holdings [Line Items]
Proportional amortization method of investment	27,988		29,110
Unfunded commitment, Proportional amortization	14,875		16,210
Amortization Expense	941	201
Tax Benefit Recognized	(1,297)	$ (281)
FHTC [Member]
Investment Holdings [Line Items]
Equity method investment	9,835		4,434
Unfunded commitment, Equity	7,425		3,104
Tax Benefit Recognized	(1,520)
CReED [Member]
Investment Holdings [Line Items]
Equity method investment	1,504		1,504
Unfunded commitment, Equity	$ 1,502		$ 1,502

Amortization method qualified affordable housing project investments commitment.

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Equity method investment qualified affordable housing project investments.

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Equity method qualified affordable housing project investments commitment.

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Investments in qualified affordable housing projects.

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Amount of affordable housing tax credits and other tax benefits recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=64813897&loc=SL49122993-202985

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Amount of investment in qualified affordable housing projects.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64813897&loc=SL49122993-202985

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Amount of amortization expense of investment in qualified affordable housing projects.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64813897&loc=SL49122993-202985

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Amount of commitment or contingent commitments to qualified affordable housing project investments.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=64813897&loc=SL49122993-202985

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