Pension and Other Postretirement Benefits Costs - Schedule of Effect of One Percentage Point Change in Assumed Health Care Cost (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
1% Increase
Effect on net periodic postretirement health care benefit cost	$ 43
Effect on the accumulated postretirement benefit obligation	622
1% Decrease
Effect on net periodic postretirement health care benefit cost	39
Effect on the accumulated postretirement benefit obligation	$ 560