Employee's Pension and Postretirement Benefits - Amounts Accrued and Unfunded Status (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Amounts Accrued
Obligation, beginning of period			$ 18,840	$ 17,977	$ 17,977
Prior Service cost					456
Interest cost	$ 100	$ 100	284	$ 400	564
Actuarial gain			0		(157)
Obligation, end of period and unfunded status	$ 19,124		$ 19,124		$ 18,840