Retirement Plans (Schedule of Costs of Retirement Plans) (Details) - Salaried Benefit Plan - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 561	$ 262	$ 1,749	$ 1,734
United States
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	415	152	1,276	1,289
Canada
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	53	46	167	164
United Kingdom
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 93	$ 64	$ 306	$ 281