Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of accumulated other comprehensive loss	$ 246,994	$ 189,516	$ 173,793	$ 168,137
Unrealized Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of accumulated other comprehensive loss	4,463	1,261	(541)
Pension Liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of accumulated other comprehensive loss	(6,983)	(7,114)	(7,402)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of accumulated other comprehensive loss	$ (2,520)	$ (5,853)	$ (7,943)	$ (9,217)