Pensions and Other Employee Benefits Plans (Components of Net Periodic Cost) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost			$ 400
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	$ 187	173
Interest cost	[2]	464	486
Expected return on plan assets	[2]	(657)	(532)
Amortization of net actuarial loss	[2]	263	232
Net periodic cost		257	359
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	[2]	4	5
Amortization of net actuarial loss	[2]		1
Amortization of prior service credits	[2]	6	6
Net periodic cost		$ 10	$ 12

[1] Included in general and administrative expenses.

[2] Included in other expense.