DERIVATIVE INSTRUMENTS (Details) (USD $)	Mar. 31, 2012	Mar. 31, 2011
Derivative [Line Items]
Average interest pay rate (in hundredths)	5.80%
Forward Commitments to Sell Fixed-Rate Mortgage Loans [Member]
Derivative [Line Items]
Notional amount	$ 213,300,000	$ 97,000,000
Difference in carrying value and fair value, reflecting a loss	98,000	168,000
Commitments To Fund Fixed-Rate Mortgage Loans [Member]
Derivative [Line Items]
Notional amount	159,100,000	77,900,000
Difference in carrying value and fair value, reflecting a gain	2,700,000	886,000
Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount	$ 479,400,000
Average maturity (in months)	59M
Average interest receive rate (in hundredths)	2.50%

The difference in the carrying value and fair value of the derivative instrument, reflecting a gain as of the reporting date.

No definition available.

Name:	bxs_DifferenceInCarryingValueAndFairValueReflectingGain
Namespace Prefix:	bxs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The difference in the carrying value and fair value of the derivative instrument, reflecting a loss as of the reporting date.

No definition available.

Name:	bxs_DifferenceInCarryingValueAndFairValueReflectingLoss
Namespace Prefix:	bxs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Monetary amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Average fixed interest rate related to the group of interest rate derivatives.

No definition available.

Name:	us-gaap_DerivativeAverageFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The average time remaining until maturity on the group of derivatives identified.

No definition available.

Name:	us-gaap_DerivativeAverageRemainingMaturity
Namespace Prefix:	us-gaap_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	instant

Average variable interest rate related to the group of interest rate derivatives.

No definition available.

Name:	us-gaap_DerivativeAverageVariableInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration