Pensions and Other Employee Benefits Plans (Components of Net Periodic Cost) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	$ 176	$ 180	$ 528	$ 541
Interest cost	[2]	441	504	1,324	1,513
Expected return on plan assets	[2]	(663)	(608)	(1,989)	(1,824)
Amortization of net actuarial loss (gain)	[2]	322	252	966	755
Net periodic cost		276	328	829	985
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	0	1	0	1
Interest cost	[2]	4	4	12	14
Expected return on plan assets	[2]	0	0	0	0
Amortization of net actuarial loss (gain)	[2]	(1)	(1)	(3)	(3)
Net periodic cost		$ 3	$ 4	$ 9	$ 12

[1] Included in general and administrative expenses.

[2] Included in other expense.