Retirement Plans - Net Periodic Pension Cost (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 272	$ 280	$ 259
Expected return on assets	(332)	(371)	(333)
Amortization of net loss	88	45	111
Net periodic pension cost	$ 28	$ (46)	$ 37