Bank Premises and Equipment - Additional Information (Detail) $ in Millions	3 Months Ended
Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Bank Premises And Equipment [Line Items]
Gain on Branch Consolidation and Sales Plan	$ 8
Branch Banking
Bank Premises And Equipment [Line Items]
Bank premises impairment	2	$ 4
St. Louis MSA to Great Southern Bank
Bank Premises And Equipment [Line Items]
Loans Sold	158
Deposits Sold	228
Premises And Equipment Sold	18
Gain on Branch Consolidation and Sales Plan	$ 8
Branch Consolidation and Sales Plan \| Disposal group classified as held for sale
Bank Premises And Equipment [Line Items]
Operating Branch Locations	60
Parcels Of Undeveloped Land	23

Amount classified as deposits disposed of

No definition available.

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- Definition

Gain included in earnings related to the Branch Consolidation and Sales Plan

+ References

No definition available.

+ Details

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- Definition

Amounts classified as loans disposed of

+ References

No definition available.

+ Details

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- Definition

Amount of operating branches management plans to sell or consolidate as a result of the Branch Consolidation and Sales Plan.

+ References

No definition available.

+ Details

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- Definition

Amount of parcels of land management plans to sell as a result of the Branch Consolidation and Sales Plan. Represents parcels of undeveloped land that had been acquired for for future branch expansion.

+ References

No definition available.

+ Details

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- Definition

Amount classified as bank premises and equipment disposed of

+ References

No definition available.

+ Details

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- Definition

The aggregate amount of write-downs for impairments recognized during the period for long-lived assets held for abandonment, exchange or sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=51824106&loc=d3e2611-110228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

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- Definition

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.

+ Details

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