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Description of the changes in valuation technique(s) and related inputs used to measure fair value.

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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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For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

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Fair Value Inputs Credit Valuation Adjustment As A Percentage Of Derivative Contract

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Fair value measurement transfers from one level to another.

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Other guarantees carrying value excluding standby letters of credit.

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Unfunded commitments deferred non-yield related loan fees and standby letters of credit carrying value.

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Fair Values of Assets and Liabilities - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair value measurement transfers from one level to another	$ 0	$ 0
Significant changes to the valuation techniques to measure fair value during the reporting period	No significant changes to the valuation techniques used by the Company to measure fair value.
Mortgage loans held for sale measured at fair value, net gain	$ 21,000,000	$ 52,000,000
Carrying value of unfunded commitments, deferred non-yield related loan fees and standby letters of credit	625,000,000		$ 618,000,000
Other guarantees carrying value	$ 189,000,000		$ 186,000,000
Minimum [Member]
Fair Value Disclosures [Abstract]
Assumed credit valuation adjustment as percentage of derivative contract fair value	0.00%
Maximum [Member]
Fair Value Disclosures [Abstract]
Assumed credit valuation adjustment as percentage of derivative contract fair value	93.00%
Average [Member]
Fair Value Disclosures [Abstract]
Assumed credit valuation adjustment as percentage of derivative contract fair value	3.00%