Comprehensive Income Changes in Accumulated Other Comprehensive Income By Component (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	$ 301,728	$ 269,584
Other comprehensive income or loss before reclassifications	3,879	2,080
Amounts reclassified from accumulated other comprehensive income	66	163
Other Comprehensive Income	3,945	2,243
Stockholders' equity, ending balance	309,398	276,609
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	(6,357)	(13,810)
Stockholders' equity, ending balance	(2,412)	(11,567)
Unrealized Gains and Losses on Available for Sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	465	(3,697)
Other comprehensive income or loss before reclassifications	4,098	2,080
Amounts reclassified from accumulated other comprehensive income	0	0
Other Comprehensive Income	4,098	2,080
Stockholders' equity, ending balance	4,563	(1,617)
Unrealized Loss on Cash Flow Swap
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	0
Other comprehensive income or loss before reclassifications	(219)
Amounts reclassified from accumulated other comprehensive income	0
Other Comprehensive Income	(219)
Stockholders' equity, ending balance	(219)
Net Actuarial Gain (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	(5,847)	(8,971)
Other comprehensive income or loss before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income	27	121
Other Comprehensive Income	27	121
Stockholders' equity, ending balance	(5,820)	(8,850)
Net Priot Service (Cost) Credit
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	(975)	(1,142)
Other comprehensive income or loss before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income	39	42
Other Comprehensive Income	39	42
Stockholders' equity, ending balance	$ (936)	$ (1,100)