Pensions and Other Employee Benefits Plans (Components of Net Periodic Cost) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost			$ 400		$ 1,200
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	$ 179	175	$ 536	526
Interest cost	[2]	464	490	1,391	1,470
Expected return on plan assets	[2]	(657)	(531)	(1,971)	(1,593)
Amortization of net actuarial loss	[2]	260	250	780	749
Net periodic cost		246	384	736	1,152
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	1		1	1
Interest cost	[2]	4	5	12	14
Amortization of net actuarial loss	[2]		1		3
Amortization of prior service credits	[2]	5	6	17	18
Net periodic cost		$ 10	$ 12	$ 30	$ 36

[1] Included in general and administrative expenses.

[2] Included in other expense.