Pension and Other Postretirement Benefits - Summary of Accumulated Other Comprehensive Loss That Have Not Been Recognized as Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	$ 56,746	$ 48,395
Net prior service cost	2,661	2,725
Total	59,407
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	(600)	(3,047)
Net prior service cost	0	$ 0
Total	$ (600)