Pension and Other Postretirement Benefit Plans - Summary of Obligations Recognized in Other Comprehensive Income (Details) - Pension Benefits - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan And Other Postretirement Benefit Plan Table Text Block [Line Items]
Net actuarial loss	$ 11,196	$ 25,595	$ 679
Amortization of actuarial loss	(6,516)	(7,362)	(6,517)
Amortization of prior service credit	1,432	1,432	1,432
Total loss (income) recognized in other comprehensive income	6,112	19,665	(4,406)
Total recognized in net periodic benefit cost and other comprehensive income	$ 11,010	$ 23,895	$ (1,524)