Retirement Plans, Amounts Recognized in Accumulated Other Comprehensive Income Table (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	$ 122	$ 153
Net actuarial loss	32,879	23,124
Amount not yet recognized in net periodic benefit cost, but recognized in accumulated other comprehensive loss	33,001	23,277
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	0	0
Net actuarial loss	73	84
Amount not yet recognized in net periodic benefit cost, but recognized in accumulated other comprehensive loss	$ 73	$ 84