Employee Benefit Plans: Funding Status of Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Benefit plan liabilities	$ 142,580		$ 142,580		$ 154,472
Other income (expense), net	(1,863)	$ 263	490	$ (526)
Pension Plan
Benefit plan liabilities	$ 50,000		$ 50,000		$ 51,000