Pension, Savings, And Other Employee Benefits - Schedule Of Components Of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8	$ 10	$ 16	$ 20
Interest cost	7,575	6,987	15,150	13,973
Expected return on plan assets	(9,173)	(8,226)	(18,346)	(16,451)
Actuarial (gain)/loss	2,435	2,956	4,870	5,912
Net periodic benefit cost/(credit)	845	1,727	1,690	3,454
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	24	34	48	67
Interest cost	351	327	702	654
Expected return on plan assets	(269)	(269)	(538)	(538)
Actuarial (gain)/loss	(117)	(91)	(234)	(182)
Net periodic benefit cost/(credit)	$ (11)	$ 1	$ (22)	$ 1