Other Comprehensive Income (Loss): Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	$ (14,054)	$ (15,044)	$ (18,589)	$ (17,422)	$ (15,044)	$ (17,422)
Other comprehensive income (loss), net of tax	(2,805)	990	(852)	(1,167)	(1,815)	(2,019)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(16,859)	(14,054)	(19,441)	(18,589)	(16,859)	(19,441)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	5,688	5,093	(8,611)	(7,133)	5,093	(7,133)
Other comprehensive income (loss), net of tax	422	595	(556)	(1,478)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	6,110	5,688	(9,167)	(8,611)	6,110	(9,167)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(19,742)	(20,137)	(9,978)	(10,289)	(20,137)	(10,289)
Other comprehensive income (loss), net of tax	(3,227)	395	(296)	311
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	$ (22,969)	$ (19,742)	$ (10,274)	$ (9,978)	$ (22,969)	$ (10,274)