Comprehensive Income: Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	$ (1,258)	$ (1,262)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(891)	(1,258)
Interest Rate Swaps, Cash Flow Hedges, AOCI | Interest Rate Swaps
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(551)	(593)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(500)	(551)
Employee Benefit Plans, AOCI
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(707)	(669)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	235	(94)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(391)	(707)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	235	(94)
Reclassification out of Accumulated Other Comprehensive Income | Interest Rate Swaps, Cash Flow Hedges, AOCI | Interest Rate Swaps
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	51	42
Reclassification out of Accumulated Other Comprehensive Income | Employee Benefit Plans, AOCI
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	81	56
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 132	$ 98