DERIVATIVE INSTRUMENTS (Details) (USD $) In Millions, unless otherwise specified					9 Months Ended
Sep. 30, 2012 Forward Commitments to Sell Fixed-Rate Mortgage Loans [Member]	Sep. 30, 2011 Forward Commitments to Sell Fixed-Rate Mortgage Loans [Member]	Sep. 30, 2012 Commitments To Fund Fixed-Rate Mortgage Loans [Member]	Sep. 30, 2011 Commitments To Fund Fixed-Rate Mortgage Loans [Member]	Sep. 30, 2012 Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount	$ 220.9	$ 167.5	$ 251.5	$ 177.7	$ 483.0
Difference in carrying value and fair value, reflecting a loss	4.4	2.4
Difference in carrying value and fair value, reflecting a gain			$ 7.1	$ 3.9
Average maturity					60 months
Average interest receive rate (in hundredths)					2.50%
Average interest pay rate (in hundredths)					5.80%

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

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

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeAverageRemainingMaturity1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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

- Details

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