Employee Benefit Plans: Changes in Level 3 Assets Measured at Fair Value on a Recurring Basis, Employee Benefits (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands |
12 Months Ended | |||||||
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Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||||||||
Defined Benefit Plan, Fair Value of Plan Assets | $ 288,622 | $ 299,533 | $ 280,362 | |||||
Fair Value, Inputs, Level 3 [Member] | ||||||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||||||||
Balance, beginning of period | 34,753 | 38,188 | ||||||
Purchase | 491 | 454 | ||||||
Unrealized gain (loss) | 1,644 | 1,789 | ||||||
Realized gain (loss) | 1 | 322 | ||||||
Settlements | 0 | (6,000) | ||||||
Balance, end of period | 36,889 | 34,753 | ||||||
Defined Benefit Plan, Fair Value of Plan Assets | 36,889 | 34,753 | ||||||
Common Collective Trust - Real Estate | ||||||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||||||||
Defined Benefit Plan, Fair Value of Plan Assets | 13,347 | 13,583 | ||||||
Common Collective Trust - Real Estate | Fair Value, Inputs, Level 3 [Member] | ||||||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||||||||
Defined Benefit Plan, Fair Value of Plan Assets | 11,143 | [1] | 9,719 | |||||
Hedge Funds | ||||||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||||||||
Defined Benefit Plan, Fair Value of Plan Assets | 25,746 | 25,034 | ||||||
Hedge Funds | Fair Value, Inputs, Level 3 [Member] | ||||||||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||||||||
Defined Benefit Plan, Fair Value of Plan Assets | $ 25,746 | [2] | $ 25,034 | |||||
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