Pensions and Other Employee Benefits Plans (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Unfunded status at end of period	$ (18,500)
Unfunded benefit obligations, discount rate	4.00%	4.25%	4.00%
Unfunded benefit obligations, decrease in discount rate	0.50%	0.50%
Change in unfunded benefit obligation as a result of decrease in half percentage point assumed discount rate	$ 3,600	$ 3,600
Accumulated pension benefit obligation	$ 48,500	$ 46,000
Expected long-term rate of return on plan assets	6.75%
Defined Benefit Plan, Actual Plan Asset Allocations	100.00%	100.00%
Employee Savings (401K) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee savings (401K) plan, maximum	6.00%
Participant's base salary rate	66.70%
Employer contributions	$ 100	$ 100	$ 100
Liquid Return Seeking [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Allocation Variance Percentage	3.00%
Defined Benefit Plan, Actual Plan Asset Allocations	61.00%
Alternative Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	9.00%
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	30.00%	43.00%
Global Equities[Member] | Liquid Return Seeking [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Allocation Percentage	75%
Marketable Real Assets[Member] | Liquid Return Seeking [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Allocation Percentage	15%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations		57.00%
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations		43.00%
Fixed Income Securities [Member] | Liquid Return Seeking [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Allocation Percentage	10%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated actuarial loss to be amortized from accumulated other comprehensive income over next fiscal year	$ 900
Contribution to qualified pension plan	2,161	$ 2,741
Estimated employer contribution next fiscal year	2,400
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to qualified pension plan	$ 32	$ 54