RETIREMENT PLANS - Net Assets and Allocations (Details) - Pension Plans - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension plan assets
Fair value of plan assets	$ 80,892	$ 75,331	$ 11,946
Weighted-average asset allocations (as a percent)	100.00%	100.00%
Level 1
Pension plan assets
Fair value of plan assets	$ 41,827	$ 62,053
Level 2
Pension plan assets
Fair value of plan assets	38,569	12,775
Level 3
Pension plan assets
Fair value of plan assets	496	503
Cash, cash equivalents, money markets and other
Pension plan assets
Fair value of plan assets	$ 6,363	$ 32,976
Weighted-average asset allocations (as a percent)	8.00%	44.00%
Cash, cash equivalents, money markets and other | Level 1
Pension plan assets
Fair value of plan assets	$ 6,363	$ 32,976
Common Stock
Pension plan assets
Fair value of plan assets	$ 28,467	$ 22,560
Weighted-average asset allocations (as a percent)	35.00%	30.00%
Common Stock | Level 1
Pension plan assets
Fair value of plan assets	$ 25,312	$ 21,344
Common Stock | Level 2
Pension plan assets
Fair value of plan assets	3,155	1,216
Mutual funds - equities
Pension plan assets
Fair value of plan assets	$ 9,248	$ 7,141
Weighted-average asset allocations (as a percent)	11.00%	9.00%
Mutual funds - equities | Level 1
Pension plan assets
Fair value of plan assets	$ 9,248	$ 6,180
Mutual funds - equities | Level 2
Pension plan assets
Fair value of plan assets		961
Exchange traded funds - equities
Pension plan assets
Fair value of plan assets	$ 904	$ 1,553
Weighted-average asset allocations (as a percent)	1.00%	2.00%
Exchange traded funds - equities | Level 1
Pension plan assets
Fair value of plan assets	$ 904	$ 1,553
Fixed income securities
Pension plan assets
Fair value of plan assets	$ 35,414	$ 10,598
Weighted-average asset allocations (as a percent)	44.00%	14.00%
Fixed income securities | Level 2
Pension plan assets
Fair value of plan assets	$ 35,414	$ 10,598
Annuities
Pension plan assets
Fair value of plan assets	$ 496	$ 503
Weighted-average asset allocations (as a percent)	1.00%	1.00%
Annuities | Level 3
Pension plan assets
Fair value of plan assets	$ 496	$ 503