Accumulated Other Comprehensive Income Reclassification out of AOCI to RE (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (23,328)		$ (23,328)			$ (8,658)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	124	$ (246)	712	$ (210)
Reclassification adjustment for net realized (gain)/ loss included in net income	0	(141)	0	(152)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	187	(206)	201	(386)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(187)	65	(201)	234
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax	(1,953)	4,239	(14,848)	6,322
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(63)	(40)	511	176
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	(1)	0	(1)	(12)
Other comprehensive income/ (loss), net of tax	(2,015)	4,199	(14,336)	6,510
Cumulative Effect of New Accounting Principle in Period of Adoption					$ 5
Accounting Standards Update 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					(339)
Accounting Standards Update 2017-12 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					5
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(23,328)	(6,038)	(23,328)	(6,038)		(8,658)	$ (12,548)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			(14,135)	6,276
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			201	(234)
Other comprehensive income/ (loss), net of tax			(14,336)	6,510
Cumulative Effect of New Accounting Principle in Period of Adoption					(334)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(23,327)	(4,872)	(23,327)	(4,872)		(8,140)	(11,194)
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Reclassification Adjustments, after Tax			(14,848)	6,474
Reclassification adjustment for net realized (gain)/ loss included in net income			0	(152)
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax			(14,848)	6,322
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] | Accounting Standards Update 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					(339)
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	848	(429)	848	(429)		332	(605)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax			712	(210)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax			201	(386)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax			511	176
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Accounting Standards Update 2017-12 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					5
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (849)	$ (737)	(849)	(737)		$ (850)	$ (749)
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax			(1)	(12)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax			0	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax			$ (1)	$ (12)
Cumulative Effect of New Accounting Principle in Period of Adoption					$ 0