Pensions and Other Employee Benefits Plans (Components of Net Periodic Cost) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost			$ 400		$ 800
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	$ 170	178	$ 357	351
Interest cost	[2]	463	494	927	980
Expected return on plan assets	[2]	(657)	(530)	(1,314)	(1,062)
Amortization of net actuarial loss	[2]	257	267	520	499
Net periodic cost		233	409	490	768
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]		1		1
Interest cost	[2]	4	4	8	9
Amortization of net actuarial loss	[2]		1		2
Amortization of prior service credits	[2]	6	6	12	12
Net periodic cost		$ 10	$ 12	$ 20	$ 24

[1] Included in general and administrative expenses.

[2] Included in other expense.