STOCK INCENTIVE AND STOCK OPTION PLANS (Details) - USD ($) $ in Thousands	1 Months Ended												12 Months Ended
	May 31, 2016	Jan. 31, 2016	May 31, 2015	Jan. 31, 2015	May 31, 2014	Jan. 31, 2014	May 31, 2013	Mar. 31, 2013	Jan. 31, 2013	Nov. 30, 2012	Jun. 30, 2012	Jan. 31, 2012	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercisable period of options, minimum (in years)													1 year
Exercisable period of options, maximum (in years)													10 years
Period for recognition of unrecognized expenses (in years)													3 years 7 months 6 days
Equity instruments other than options [Abstract]
Number of awards granted (in shares)	27,024		24,750		19,500
Shares of stock covered by award (in shares)	27,024		24,750		19,500
Long-Term Equity Incentive plan [Member] | Shares To Be Issued In 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)															$ 554
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)														$ 22	843,000,000
Assumptions used for stock options [Abstract]
Intrinsic value of stock options exercised													$ 798	2,500	4,600
Restricted Stock Units [Member] | Long-Term Equity Incentive plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)													37	107	180
Equity instruments other than options [Abstract]
Number of awards granted (in shares)							7,500				60,000
Shares of stock covered by award (in shares)							7,500				60,000
Period of issuance of restricted stock units											5 years
Restricted Stock Units [Member] | Long-Term Equity Incentive plan [Member] | Awarded To Directors In 2010, 2012 And 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)													622	510	$ 330
Restricted Stock Units [Member] | Long-Term Equity Incentive plan [Member] | Shares To Be Issued In 2017 [Member]
Equity instruments other than options [Abstract]
Number of awards granted (in shares)										24,083
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
bxs_Sharebasedcompensationsharebasedpaymentarrangementsotherthanstockoptionsunrecognizedcostassociatedwithawardsnotyetvested													$ 14,400
Compensation expense recognized (reversed)														$ 63
Equity instruments other than options [Abstract]
Number of awards granted (in shares)													297,251	273,269	349,900
Restricted Stock [Member] | Long-Term Equity Incentive plan [Member]
Equity instruments other than options [Abstract]
Number of awards granted (in shares)													297,251	273,269	349,900
Restricted Stock [Member] | Long-Term Equity Incentive plan [Member] | Shares To Be Issued In 2015 [Member]
Equity instruments other than options [Abstract]
Number of awards granted (in shares)										88,232					64,500
Restricted Stock [Member] | Long-Term Equity Incentive plan [Member] | Shares To Be Issued In 2018 [Member]
Equity instruments other than options [Abstract]
Number of awards granted (in shares)								592,500						8,700	51,500
Restricted Stock [Member] | Long-Term Equity Incentive plan [Member] | Shares To Be Issued In 2019 [Member]
Equity instruments other than options [Abstract]
Number of awards granted (in shares)													16,750	6,500	207,650
Restricted Stock [Member] | Long-Term Equity Incentive plan [Member] | Shares To Be Issued in 2020 [Member]
Equity instruments other than options [Abstract]
Number of awards granted (in shares)														258,069	26,250
Restricted Stock [Member] | Long-Term Equity Incentive plan [Member] | Shares to Be Issued in 2021 [Member]
Equity instruments other than options [Abstract]
Number of awards granted (in shares)													203,000
Restricted Stock [Member] | Long-Term Equity Incentive plan [Member] | Shares To Be Issued in 2023 [Member]
Equity instruments other than options [Abstract]
Number of awards granted (in shares)													77,500
Restricted Stock [Member] | Long-Term Equity Incentive plan [Member] | Shares To Be Issued Beginning In March 2014 [Member]
Equity instruments other than options [Abstract]
Number of awards granted (in shares)								21,341
Period of issuance of restricted stock units													3 years
2014 grant of Restricted Stock [Member] | Long-Term Equity Incentive plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)													$ 1,200	$ 1,300	$ 2,200
2015 Grant of Restricted Stock [Member] | Long-Term Equity Incentive plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)													1,200	1,000
2016 Grant of restricted Stock [Member] | Long-Term Equity Incentive plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)													1,000
2012 grant of performance shares [Member]
Equity instruments other than options [Abstract]
Number of awards granted (in shares)												103,055
2012 grant of performance shares [Member] | Long-Term Equity Incentive plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)													153		153
2013 grant of performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)														458	477
Equity instruments other than options [Abstract]
Number of awards granted (in shares)									83,620
2013 grant of performance shares [Member] | Long-Term Equity Incentive plan [Member]
Additional general disclosures [Abstract]
Vesting period, description									two-year performance period from January 1, 2013 through December 31, 2014
2014 grant of performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)													575	842	$ 500
Equity instruments other than options [Abstract]
Number of awards granted (in shares)						57,550
2015 grant of performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)													1,000	$ 1,300
Equity instruments other than options [Abstract]
Number of awards granted (in shares)				84,494
2016 grant of performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized (reversed)													$ 210
Equity instruments other than options [Abstract]
Number of awards granted (in shares)		99,277