PENSION, OTHER POST RETIREMENT BENEFIT AND PROFIT SHARING PLANS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
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	$ 259,511	$ 263,497	$ 201,696
Service cost	8,852	10,460	8,936
Interest cost	9,364	10,351	9,358
Actuarial loss	9,302	(14,308)	53,131
Benefits paid	(10,343)	(10,078)	(9,029)
Administrative expenses paid	(702)	(411)	(595)
Projected benefit obligations at end of year	275,984	259,511	263,497
Change in plans' assets:
Fair value of plans assets at beginning of year	195,019	201,352	196,447
Actual return on assets	11,745	1,761	12,525
Employer contributions	19,395	2,395	2,004
Benefits paid	(10,343)	(10,078)	(9,029)
Administrative expenses paid	(702)	(411)	(595)
Fair value of plans assets at end of year	215,114	195,019	201,352
Funded status:
Projected benefit obligations	(259,511)	(263,497)	(201,696)	$ (275,984)	$ (259,511)	$ (263,497)
Fair value of plans assets	195,019	201,352	196,447	215,114	195,019	201,352
Net amount recognized				(60,870)	(64,492)	(62,145)
Amounts recognized in the consolidated balance sheets consisted of:
Prepaid benefit cost				57,048	50,724	64,838
Accrued benefit liability				(25,352)	(24,617)	(23,902)
Accumulated other comprehensive income adjustment				(92,566)	(90,599)	(103,081)
Net amount recognized				(60,870)	(64,492)	(62,145)
Pre-tax amounts recognized in accumulated other comprehensive income consisted of:
Net prior service (benefit) cost				(3,162)	(3,880)
Net actuarial loss				95,728	94,479
Total accumulated other comprehensive income				$ 92,566	$ 90,599	$ 103,081
Net transition obligation that will be amortized into net periodic cost over the next fiscal year	(743)
Recognized prior service (benefit) cost	(718)	(718)	(768)
Net actuarial loss that will be amortized into net periodic cost over the next fiscal year	6,900
Components of net periodic benefit cost:
Service cost	8,852	10,460	8,936
Interest cost	9,364	10,351	9,358
Expected return on assets	(10,453)	(10,775)	(10,534)
Amortization of unrecognized transition amount			18
Recognized prior service (benefit) cost	(718)	(718)	(768)
Recognized net loss	6,761	7,905	3,702
Net periodic benefit cost	$ 13,806	$ 17,223	$ 10,712
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)				4.10%	4.44%
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)	4.44%	4.10%	4.90%
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				$ 275,984	$ 259,511
Accumulated benefit obligation				274,326	252,949
Fair value of assets				$ 215,114	$ 195,019
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)				3.94%	4.20%
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)	4.20%	3.90%	4.50%
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)				3.35%	3.40%
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)	3.40%	3.10%	3.65%
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	$ 2,000
Fair value of plans assets at end of year	2,600	$ 2,000
Funded status:
Fair value of plans assets	$ 2,000	$ 2,000		$ 2,600	$ 2,000