PENSION, OTHER POST RETIREMENT BENEFIT AND PROFIT SHARING PLANS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Benefits as a percentage of cash balance	2.50%
Pension Benefits [Member]
Change in benefit obligations:
Projected benefit obligations at beginning of year	$ 263,497	$ 201,696	$ 213,804
Service cost	10,460	8,936	10,735
Interest cost	10,351	9,358	8,212
Amendments			10,850
Actuarial loss	(14,308)	53,131	(18,794)
Benefits paid	(10,078)	(9,029)	(22,116)
Administrative expenses paid	(411)	(595)	(995)
Projected benefit obligations at end of year	259,511	263,497	201,696
Change in plans' assets:
Fair value of plans assets at beginning of year	201,352	196,447	203,704
Actual return on assets	1,761	12,525	13,960
Employer contributions	2,395	2,004	1,894
Benefits paid	(10,078)	(9,029)	(22,116)
Administrative expenses paid	(411)	(595)	(995)
Fair value of plans assets at end of year	195,019	201,352	196,447
Funded status:
Projected benefit obligations	(263,497)	(201,696)	(213,804)	$ (259,511)	$ (263,497)	$ (201,696)
Fair value of plans assets	201,352	196,447	203,704	195,019	201,352	196,447
Net amount recognized				(64,492)	(62,145)	(5,249)
Amounts recognized in the consolidated balance sheets consisted of:
Prepaid benefit cost				50,724	64,838	72,886
Accrued benefit liability				(24,617)	(23,902)	(23,241)
Accumulated other comprehensive income adjustment				(90,599)	(103,081)	(54,894)
Net amount recognized				(64,492)	(62,145)	(5,249)
Pre-tax amounts recognized in accumulated other comprehensive income consisted of:
Net prior service (benefit) cost				(3,880)	(4,598)
Net actuarial loss				94,479	107,679
Total accumulated other comprehensive income				$ 90,599	$ 103,081	$ 54,894
Net transition obligation that will be amortized into net periodic cost over the next fiscal year	(718)
Recognized prior service (benefit) cost	(718)	(768)	(768)
Net actuarial loss that will be amortized into net periodic cost over the next fiscal year	6,800
Components of net periodic benefit cost:
Service cost	10,460	8,936	10,735
Interest cost	10,351	9,358	8,212
Expected return on assets	(10,775)	(10,534)	(10,974)
Amortization of unrecognized transition amount		18	18
Recognized prior service (benefit) cost	(718)	(768)	(768)
Recognized net loss	7,905	3,702	6,099
Special termination benefit			10,850
Net periodic benefit cost	$ 17,223	$ 10,712	$ 24,172
Basic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
General information	The Basic Plan is a non-contributory defined benefit pension plan managed by a trustee covering substantially all full-time employees who have at least one year of service and have attained the age of 21. For such employees hired prior to January 1, 2006, benefits are based on years of service and the employee's compensation
Benefits as a percentage of cash balance	2.50%
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate (in hundredths)				4.44%	4.10%
Rate of compensation increase (in hundredths)				3.00%	3.00%
Weighted-average assumptions used to determine net periodic benefit cost [Abstract]
Discount rate (in hundredths)	4.10%	4.90%	4.05%
Rate of compensation increase (in hundredths)	3.00%	3.00%	3.00%
Expected rate of return on plan assets (in hundredths)	5.50%	5.50%	5.50%
Restoration Plan and Supplemental Plan [Member]
Accumulated benefit obligations in excess of plan assets [Abstract]
Projected benefit obligation				$ 259,511	$ 263,497
Accumulated benefit obligation				252,949	252,227
Fair value of assets				$ 195,019	$ 201,352
Restoration Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
General information	The Restoration Plan provides for the payment of retirement benefits to certain participants in the Basic Plan.
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate (in hundredths)				4.20%	3.90%
Rate of compensation increase (in hundredths)				3.00%	3.00%
Weighted-average assumptions used to determine net periodic benefit cost [Abstract]
Discount rate (in hundredths)	3.90%	4.50%	3.65%
Rate of compensation increase (in hundredths)	3.00%	3.00%	3.00%
Supplemental Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
General information	The Supplemental Plan is a non-qualified defined benefit supplemental retirement plan for certain key employees. Benefits commence when the employee retires and are payable over a period of ten years.
Period after employee retirement during which benefits are payable	10 years
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate (in hundredths)				3.40%	3.10%
Rate of compensation increase (in hundredths)				3.00%	3.00%
Weighted-average assumptions used to determine net periodic benefit cost [Abstract]
Discount rate (in hundredths)	3.10%	3.65%	2.85%
Rate of compensation increase (in hundredths)	3.00%	3.00%	3.00%
BancorpSouth, Inc. (Parent Company Only) [Member] | Basic Plan [Member]
Change in plans' assets:
Fair value of plans assets at beginning of year	$ 1,900
Fair value of plans assets at end of year	2,000	$ 1,900
Funded status:
Fair value of plans assets	$ 1,900	$ 1,900		$ 2,000	$ 1,900