Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 1,732	$ (3,262)	$ (456)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	4,687	(2,096)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	9	(710)
Other Comprehensive Income (Loss), Net of Tax	4,696	(2,806)	(2,528)
AOCI reclass related to TCJA enactment	298
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	398	0	0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	328	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Net of Tax	328	0
AOCI reclass related to TCJA enactment	70
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,564)	(2,906)	(3,195)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	1,610	289
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Net of Tax	1,610	289
AOCI reclass related to TCJA enactment	(268)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	2,898	(356)	$ 2,739
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	2,749	(2,385)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	9	(710)
Other Comprehensive Income (Loss), Net of Tax	2,758	$ (3,095)
AOCI reclass related to TCJA enactment	$ 496