FEDERAL INCOME TAX (Net Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax liabilities
Deferred policy acquisition costs	$ 18,289	$ 19,801
Investments in partnerships	964	2,156
Prepaid pension cost	4,553	4,441
Net bond discount accretion	383	357
Depreciation	4,187	1,908
Revaluation of investment basis	325	377
Identifiable intangible assets	1,391	1,540
Capitalized Software	4,891	0
Other	1,568	1,416
Gross deferred tax liability	91,729	93,216
Deferred tax assets
Financial statement reserves in excess of income tax reserves	23,851	20,845
Unearned premium adjustment	18,979	20,816
Net operating loss carryforwards	0	1,708
Underfunded benefit plan obligation	4,295	9,072
Post-retirement benefits other than pensions	9,533	10,785
Other-than-temporary impairment of investments	1,974	2,094
Compensation expense related to stock options	2,307	2,394
Nonqualified deferred compensation	2,066	1,623
Other	3,795	3,293
Deferred tax asset	66,800	72,630
Net deferred tax liability	24,929	20,586
Equity securities
Deferred tax liabilities
Net unrealized appreciation on investment securities	33,096	48,652
All other securities
Deferred tax liabilities
Net unrealized appreciation on investment securities	$ 22,082	$ 12,568