INCOME TAXES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allocation of income taxes [Abstract]
Income tax expense (benefit)	$ 59,248	$ 50,652	$ 37,551
Shareholders' equity for other comprehensive income	1,145	(8,481)	(13,249)
Shareholders' equity for stock option plans	(1,079)	(1,856)	(139)
Total	59,314	40,315	24,163
Current [Abstract]
Federal	62,369	51,014	32,729
State	8,235	7,201	1,570
Deferred [Abstract]
Federal	(10,391)	(6,870)	1,774
State	(965)	(693)	1,478
Income Tax Expense (Benefit), Total	$ 59,248	$ 50,652	$ 37,551
Statutory federal income tax rate (in hundredths)	35.00%	35.00%	35.00%
Income tax reconciliation [Abstract]
Reversal of deferred tax asset	$ 1,600	$ 785
Tax expense at statutory rates	65,359	58,591	$ 46,083
Increase (decrease) in taxes resulting from [Abstract]
State income taxes, net of federal tax benefit	4,709	4,230	1,926
Tax-exempt interest revenue	(6,881)	(7,371)	(7,423)
Tax-exempt earnings on life insurance	(2,589)	(3,076)	(2,889)
Deductible dividends paid on 401(k) plan	(617)	(458)	(187)
Tax Credits	1,871	1,771	578
Meals and Entertainment	481	486	489
Other, net	657	21	130
Income Tax Expense (Benefit), Total	59,248	50,652	37,551
Deferred tax assets [Abstract]
Loans, principally due to allowance for credit losses	47,825	53,922
Other real estate owned	3,069	4,605
Mark to market - securities	4,160	4,164
Accrued liabilities, principally due to compensation arrangements and vacation accruals	24,153	17,877
Other	106	129
Unrecognized pension expense	34,654	39,428
Total gross deferred tax assets	$ 113,967	$ 120,125
Less: valuation allowance
Deferred tax assets	$ 113,967	$ 120,125
Deferred tax liabilities [Abstract]
Lease transactions	18,868	25,033
Employment benefits	736	7,435
Premises and equipment, principally due to differences in depreciation	19,294	21,845
Mortgage servicing rights	21,652	19,409
Intangible assets	11,310	11,024
Investments, principally due to interest income recognition	2,387	592
Deferred loan points	4,785	3,851
Other assets, principally due to expense recognition	9	959
Unrealized net losses on available-for-sale securities	8,764	12,393
Total gross deferred tax liabilities	87,805	102,541
Net deferred tax liabilities	$ 26,162	$ 17,584
Activity in unrecognized tax benefits [Roll Forward]
Unrecognized tax benefit, January 1			1,571
Gross decreases - tax positions in prior period			$ (1,571)
Settlements
Lapse of statute of limitations
Tax benefit recorded as result of resolution of uncertain tax position	$ 1,600
BancorpSouth, Inc. (Parent Company Only) [Member]
Allocation of income taxes [Abstract]
Income tax expense (benefit)	(2,818)	$ (2,420)	$ (5,860)
Deferred [Abstract]
Income Tax Expense (Benefit), Total	(2,818)	(2,420)	(5,860)
Increase (decrease) in taxes resulting from [Abstract]
Income Tax Expense (Benefit), Total	$ (2,818)	$ (2,420)	$ (5,860)