Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of accumulated other comprehensive (loss) income	$ 120,754	$ 114,715	$ 114,545	$ 110,022
Unrealized Gains on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of accumulated other comprehensive (loss) income	1,679	1,164	1,902
Pension Liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of accumulated other comprehensive (loss) income	(5,552)	(5,890)	(5,043)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of accumulated other comprehensive (loss) income	$ (3,873)	$ (4,726)	$ (3,141)	$ (2,723)