Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018		Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	$ 233,630	$ 205,009	$ 219,830	[1]	$ 201,505
Other Comprehensive Income (Loss), Net of Tax	2,130	(2,620)
Accumulated Pension Plan Adjustment Net Unamortized Gain Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	(328)		0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(328)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0
Other Comprehensive Income (Loss), Net of Tax	(328)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	139	398	139		398
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Net of Tax	0	0
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	(323)	(849)	(314)		(1,564)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(9)	715
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Net of Tax	(9)	715
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	1,626	(437)	(841)		2,898
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	2,465	(2,779)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	2	(556)
Other Comprehensive Income (Loss), Net of Tax	2,467	(3,335)
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	1,114	(888)	$ (1,016)		$ 1,732
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	2,128	(2,064)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	2	(556)
Other Comprehensive Income (Loss), Net of Tax	$ 2,130	$ (2,620)

[1] Derived from audited consolidated financial statements