RETIREMENT PLANS - Net Assets and Allocations (Details) - Pension Plans - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension plan assets
Fair value of plan assets	$ 89,352	$ 83,350	$ 77,530
Weighted-average asset allocations (as a percent)	100.00%	100.00%
Level 1
Pension plan assets
Fair value of plan assets	$ 49,123	$ 53,533
Level 2
Pension plan assets
Fair value of plan assets	40,229	29,380
Level 3
Pension plan assets
Fair value of plan assets		437
Cash, cash equivalents, money markets and other
Pension plan assets
Fair value of plan assets	$ 5,037	$ 4,982
Weighted-average asset allocations (as a percent)	6.00%	6.00%
Cash, cash equivalents, money markets and other | Level 1
Pension plan assets
Fair value of plan assets	$ 5,037	$ 4,982
Common Stock
Pension plan assets
Fair value of plan assets	$ 27,785	$ 26,702
Weighted-average asset allocations (as a percent)	31.00%	32.00%
Common Stock | Level 1
Pension plan assets
Fair value of plan assets	$ 24,781	$ 22,451
Common Stock | Level 2
Pension plan assets
Fair value of plan assets	3,004	4,251
Mutual funds - fixed income
Pension plan assets
Fair value of plan assets	$ 9,494	$ 12,970
Weighted-average asset allocations (as a percent)	11.00%	16.00%
Mutual funds - fixed income | Level 1
Pension plan assets
Fair value of plan assets	$ 9,494	$ 12,970
Mutual funds - equities
Pension plan assets
Fair value of plan assets	$ 8,278	$ 10,921
Weighted-average asset allocations (as a percent)	9.00%	13.00%
Mutual funds - equities | Level 1
Pension plan assets
Fair value of plan assets	$ 8,278	$ 10,921
Fixed income securities
Pension plan assets
Fair value of plan assets	$ 37,225	$ 26,307
Weighted-average asset allocations (as a percent)	41.00%	32.00%
Fixed income securities | Level 1
Pension plan assets
Fair value of plan assets		$ 1,178
Fixed income securities | Level 2
Pension plan assets
Fair value of plan assets	$ 37,225	25,129
Other
Pension plan assets
Fair value of plan assets	$ 1,533	$ 1,468
Weighted-average asset allocations (as a percent)	2.00%	1.00%
Other | Level 1
Pension plan assets
Fair value of plan assets	$ 1,533	$ 1,031
Other | Level 3
Pension plan assets
Fair value of plan assets		$ 437