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Rollforward of Financial Instruments Classified in Level Three of Valuation Hierarchy (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest rate lock commitments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance		$ 982
Total Realized/Unrealized (Losses)/Gains Recorded in (Loss)/ Income		1,467
Total Realized/Unrealized (Losses)/Gain Recorded in Comprehensive (Loss) Income		0
Transfers to/(from) level 3		0
Fair Value, Ending Balance		2,449
Change in Unrealized Gains/(Losses) Related to Instruments Held		2,430
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Beginning Balance	$ 2,729	228,099
Total Realized/Unrealized (Losses)/Gains Recorded in (Loss)/ Income	(154)	(2,726)
Total Realized/Unrealized (Losses)/Gain Recorded in Comprehensive (Loss) Income	0	0
Issuances		7,574
Settlements		(4,147)
Transfers to/(from) level 3	0	0
Fair Value, Ending Balance	2,575	228,800
Change in Unrealized Gains/(Losses) Related to Instruments Held	$ (154)	$ (2,726)

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Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Change in Unrealized Gains (Losses) Related to Instruments Held

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ 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 (c)(1)
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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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-Section 50
-Paragraph 2
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Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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