Stockholders' Equity - Reclassifications From Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax	$ 25	$ 23	$ 75	$ 69
Prior service cost
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	13	12	39	38
Actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	12	11	36	31
Defined Benefit Pension and Postretirement Items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	25	23	75	69
Tax effect	$ 0	$ 0	$ 0	$ 0