Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income (Loss) by Component, Net of Tax (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 54,073,000	$ 52,839,000
Other comprehensive income before reclassification	258,000	879,000
Amounts reclassified from accumulated other comprehensive income (loss)	0	(1,000)
Net current period other comprehensive income	258,000	878,000
Balance at end of period	54,761,000	54,007,000
Unrealized Gains and Losses on Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(679,000)	(248,000)
Other comprehensive income before reclassification	258,000	879,000
Amounts reclassified from accumulated other comprehensive income (loss)	0	(1,000)
Net current period other comprehensive income	258,000	878,000
Balance at end of period	(421,000)	630,000
Defined Benefit Pension Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(3,812,000)	(3,514,000)
Other comprehensive income before reclassification	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Net current period other comprehensive income	0	0
Balance at end of period	(3,812,000)	(3,514,000)
Totals
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(4,491,000)	(3,762,000)
Balance at end of period	$ (4,233,000)	$ (2,884,000)