Pensions and Other Employee Benefits Plans (Components of Net Periodic 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 [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	$ 183	$ 170	$ 361	$ 357
Interest cost	[2]	499	463	1,009	927
Expected return on plan assets	[2]	(609)	(657)	(1,216)	(1,314)
Amortization of net actuarial loss (gain)	[2]	272	257	503	520
Net periodic cost		345	233	657	490
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	[2]	5	4	10	8
Amortization of net actuarial loss (gain)	[2]	(1)		(2)
Amortization of prior service cost (credit)	[2]		6		12
Net periodic cost		$ 4	$ 10	$ 8	$ 20

[1] Included in general and administrative expenses.

[2] Included in other expense.