BENEFIT PLANS: Defined Benefit Plan, Estimated Future Benefit Payments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Pension Plan
Defined Benefit Plan Disclosure
Defined Benefit Plan, Expected Future Benefit Payments in Year One	$ 23,882
Defined Benefit Plan, Expected Future Benefit Payments in Year Two	25,591
Defined Benefit Plan, Expected Future Benefit Payments in Year Three	27,490
Defined Benefit Plan, Expected Future Benefit Payments in Year Four	29,729
Defined Benefit Plan, Expected Future Benefit Payments in Year Five	32,179
Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter	199,630
Senior Management Security Plan
Defined Benefit Plan Disclosure
Defined Benefit Plan, Expected Future Benefit Payments in Year One	3,721
Defined Benefit Plan, Expected Future Benefit Payments in Year Two	3,948
Defined Benefit Plan, Expected Future Benefit Payments in Year Three	4,130
Defined Benefit Plan, Expected Future Benefit Payments in Year Four	4,129
Defined Benefit Plan, Expected Future Benefit Payments in Year Five	4,326
Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter	$ 23,932