Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Dec. 31, 2016		Jun. 30, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	$ 389	$ (418)	$ 389	$ (418)	$ (307)	$ (3,262)	[1]	$ (121)	$ (456)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	712	(259)	3,688	565
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(16)	(38)	(37)	(527)
Other Comprehensive Income (Loss), Net of Tax	696	(297)	3,651	38
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	219		219		219	0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0		219
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0		0
Other Comprehensive Income (Loss), Net of Tax	0		219
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	(1,925)	(4,527)	(1,925)	(4,527)	(2,238)	(2,905)		(5,135)	(3,195)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	313	608	980	(1,332)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax	313	608	980	(1,332)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss)	2,095	4,109	2,095	4,109	$ 1,712	$ (357)		$ 5,014	$ 2,739
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	399	(867)	2,489	1,897
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(16)	(38)	(37)	(527)
Other Comprehensive Income (Loss), Net of Tax	$ 383	$ (905)	$ 2,452	$ 1,370

[1] Derived from audited consolidated financial statements