Note 5. Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2014

Qualified Pension Plans [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Net Benefit Costs [Table Text Block]

	Qualified Pension Plans
	Three Months Ended September 30,						Nine Months Ended September 30,
(Dollars in thousands)	2014			2013			2014			2013
Interest cost on benefit obligation	$	18,820		$	17,506		$	56,458		$	52,517
Expected return on plan assets	(23,319		)	(22,831		)	(69,955		)	(68,493		)
Amortization of actuarial loss	2,424			4,568			7,274			13,704
Amortization of prior-service costs	405			418			1,214			1,253
Net periodic benefit income	$	(1,670	)	$	(339	)	$	(5,009	)	$	(1,019	)

Non Qualified Pension Plans [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Net Benefit Costs [Table Text Block]

	Non-Qualified Pension Plans
	Three Months Ended September 30,				Nine Months Ended September 30,
(Dollars in thousands)	2014		2013		2014		2013
Interest cost on benefit obligation	$	862	$	803	$	2,588	$	2,410
Amortization of actuarial loss	219		280		657		839
Amortization of prior-service costs	2		1		4		4
Net periodic benefit expense	$	1,083	$	1,084	$	3,249	$	3,253

Postretirement Medical Plan [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Net Benefit Costs [Table Text Block]

	Three Months Ended September 30,						Nine Months Ended September 30,
(Dollars in thousands)	2014			2013			2014			2013
Service cost	$	170		$	370		$	712		$	1,112
Interest cost on benefit obligation	708			869			2,051			2,608
Amortization of actuarial gain	(271		)	—			(1,584		)	—
Amortization of prior-service credit	(715		)	(263		)	(2,147		)	(789		)
Net periodic benefit expense (income)	$	(108	)	$	976		$	(968	)	$	2,931