INCOME TAXES (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allocation of income taxes [Abstract]
Income tax expense (benefit)	$ 50,652,000	$ 37,551,000	$ 33,252,000
Shareholders' equity for other comprehensive income	(8,481,000)	(13,249,000)	(3,943,000)
Shareholders' equity for stock option plans	(1,856,000)	(139,000)	32,000
Total	40,315,000	24,163,000	29,341,000
Current [Abstract]
Federal	51,014,000	32,729,000	34,316,000
State	7,201,000	1,570,000	3,389,000
Deferred [Abstract]
Federal	(6,870,000)	1,774,000	(4,964,000)
State	(693,000)	1,478,000	511,000
Income Tax Expense (Benefit), Total	50,652,000	37,551,000	33,252,000
Statutory federal income tax rate (in hundredths)	35.00%	35.00%	35.00%
Income tax reconciliation [Abstract]
Reversal of deferred tax asset	785,000	1,100,000
Tax expense at statutory rates	58,591,000	46,083,000	41,141,000
Increase (decrease) in taxes resulting from [Abstract]
State income taxes, net of federal tax benefit	4,230,000	1,926,000	2,453,000
Tax-exempt interest revenue	(7,371,000)	(7,423,000)	(7,789,000)
Tax-exempt earnings on life insurance	(3,076,000)	(2,889,000)	(2,790,000)
Deductible dividends paid on 401(k) plan	(458,000)	(187,000)	(100,000)
Tax credits	(1,771,000)	(578,000)	(466,000)
Other, net	507,000	619,000	803,000
Income Tax Expense (Benefit), Total	50,652,000	37,551,000	33,252,000
Deferred tax assets [Abstract]
Loans, principally due to allowance for credit losses	53,922,000	58,003,000
Other real estate owned	4,605,000	6,799,000
Mark to market - securities	4,164,000	4,164,000
Accrued liabilities, principally due to compensation arrangements and vacation accruals	17,877,000	13,085,000
Other	129,000	2,993,000
Unrecognized pension expense	39,428,000	20,997,000
Total gross deferred tax assets	120,125,000	106,041,000
Less: valuation allowance
Deferred tax assets	120,125,000	106,041,000
Deferred tax liabilities [Abstract]
Lease transactions	25,033,000	29,997,000
Employment benefits	7,435,000	12,483,000
Premises and equipment, principally due to differences in depreciation	21,845,000	23,488,000
Mortgage servicing rights	19,409,000	20,679,000
Intangible assets	11,024,000	10,654,000
Investments, principally due to interest income recognition	592,000	133,000
Deferred loan points	3,851,000	2,806,000
Other assets, principally due to expense recognition	959,000	1,033,000
Unrealized net losses on available-for-sale securities	12,393,000	2,289,000
Total gross deferred tax liabilities	102,541,000	103,562,000
Net deferred tax liabilities	17,584,000	2,479,000
Activity in unrecognized tax benefits [Roll Forward]
Unrecognized tax benefit, January 1		1,571,000	1,102,000
Gross increases - tax positions in prior period			199,000
Gross decreases - tax positions in prior period		(1,571,000)
Gross increases - tax positions in current period			270,000
Settlements
Lapse of statute of limitations
Unrecognized tax benefit, December 31			1,571,000
Tax benefits that, if recognized, would affect the effective tax rate			1,600,000
Interest related to unrecognized tax benefits		329,000	329,000
Liability for interest			560,000
Tax benefit recorded as result of resolution of uncertain tax position	1,600,000
BancorpSouth, Inc. (Parent Company Only) [Member]
Allocation of income taxes [Abstract]
Income tax expense (benefit)	(2,420,000)	(5,860,000)	(5,732,000)
Deferred [Abstract]
Income Tax Expense (Benefit), Total	(2,420,000)	(5,860,000)	(5,732,000)
Increase (decrease) in taxes resulting from [Abstract]
Income Tax Expense (Benefit), Total	$ (2,420,000)	$ (5,860,000)	$ (5,732,000)