Supplemental Comprehensive Income Disclosures (Details 2) - 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]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	$ (11,341)
Cumulative Effect of New Accounting Principle in Period of Adoption				$ 0
Other comprehensive income (loss) before reclassification adjustment	7,134	$ (3,145)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	105	(103)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	0	0
Total other comprehensive (loss) income	7,239	(5,492)
Accumulated Other Comprehensive Income (Loss), Ending Balance	(4,102)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	(11,697)	(7,510)
Cumulative Effect of New Accounting Principle in Period of Adoption				(1,344)
Other comprehensive income (loss) before reclassification adjustment	7,134	(3,145)
Amounts reclassified from accumulated other comprehensive income (loss)	0	(2,244)
Total other comprehensive (loss) income	7,134	(5,389)
Accumulated Other Comprehensive Income (Loss), Ending Balance	(4,563)	(12,899)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	461	299
Cumulative Effect of New Accounting Principle in Period of Adoption				0
Other comprehensive income (loss) before reclassification adjustment	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive (loss) income	0	0
Accumulated Other Comprehensive Income (Loss), Ending Balance	461	299
Derivative [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	(105)	(306)
Cumulative Effect of New Accounting Principle in Period of Adoption				0
Total other comprehensive (loss) income	105	(103)
Accumulated Other Comprehensive Income (Loss), Ending Balance	0	(409)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	(11,341)	(7,517)
Cumulative Effect of New Accounting Principle in Period of Adoption				$ (1,344)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	7,239	(3,248)
Amounts reclassified from accumulated other comprehensive income (loss)	0	(2,244)
Total other comprehensive (loss) income	7,239	(5,492)
Accumulated Other Comprehensive Income (Loss), Ending Balance	(4,102)	(13,009)
Previously Reported [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	(11,697)	(6,166)
Previously Reported [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	461	299
Previously Reported [Member] | Derivative [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	(105)	(306)
Previously Reported [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Beginning Balance	$ (11,341)	$ (6,173)
Effect of ASU Adoption [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption			$ 0
Effect of ASU Adoption [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption			0
Effect of ASU Adoption [Member] | Derivative [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption			0
Effect of ASU Adoption [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption			$ 0