EMPLOYEE BENEFITS - Amounts Recognized as a Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Pension Plan
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net (loss) gain		$ (28,928)	$ (28,859)
Prior service cost		(123)	(109)
Accumulated other comprehensive (loss) income, before tax		(29,051)	(28,968)
Deferred tax benefit (expense)		6,100	9,674
Reclassification of Certain Tax Effects	[1]	0	(3,591)
Accumulated other comprehensive (loss) income, net of tax		(22,951)	(22,885)
Defined Benefit Pension Plan Acquired
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net (loss) gain		(171)	(102)
Prior service cost		0	0
Accumulated other comprehensive (loss) income, before tax		(171)	(102)
Deferred tax benefit (expense)		35	15
Reclassification of Certain Tax Effects	[1]	0	6
Accumulated other comprehensive (loss) income, net of tax		(136)	(81)
Restoration Plan
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net (loss) gain		(3,984)	(4,317)
Prior service cost		(24)	(31)
Accumulated other comprehensive (loss) income, before tax		(4,008)	(4,348)
Deferred tax benefit (expense)		841	1,276
Reclassification of Certain Tax Effects	[1]	0	(364)
Accumulated other comprehensive (loss) income, net of tax		$ (3,167)	$ (3,436)

[1] Amounts reclassified to retained earnings due to early adoption of ASU 2018-02. See “Note 1 – Summary of Significant Accounting and Reporting Policies” for further information.