Pension, Savings, and Other Employee Benefits - Schedule of Amounts Recognized in Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial (gain)/loss arising during measurement period	$ (14,371)	$ 13,643
Prior service cost/(credit) arising during measurement period	0	0
Items amortized during the measurement period:
Prior service credit/(cost)	0	0
Actuarial (gain)/loss	(9,888)	(12,102)
Total recognized in other comprehensive income	(24,259)	1,541
Other Benefits
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial (gain)/loss arising during measurement period	4,629	(1,646)
Prior service cost/(credit) arising during measurement period	408	0
Items amortized during the measurement period:
Prior service credit/(cost)	(32)	0
Actuarial (gain)/loss	299	288
Total recognized in other comprehensive income	$ 5,304	$ (1,358)