Note 5. Shareholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, beginning	$ (355,532)	$ (268,355)	$ (354,409)	$ (269,531)
Other comprehensive income (loss) before reclassifications	173	(439)	(2,891)	(317)
Other comprehensive income (loss) before reclassifications	173	(439)	(2,891)	(317)
Amounts reclassified from accumulated other comprehensive loss	1,951	992	3,892	2,046
Accumulated other comprehensive income (loss), net of tax, ending	(353,408)	(267,802)	(353,408)	(267,802)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, beginning	(6,219)	(302)	(3,155)	(424)
Other comprehensive income (loss) before reclassifications	173	(439)	(2,891)	(317)
Amounts reclassified from accumulated other comprehensive loss	0	0	0	0
Accumulated other comprehensive income (loss), net of tax, ending	(6,046)	(741)	(6,046)	(741)
Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax, beginning	(349,313)	(268,053)	(351,254)	(269,107)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive loss	1,951	992	3,892	2,046
Accumulated other comprehensive income (loss), net of tax, ending	$ (347,362)	$ (267,061)	$ (347,362)	$ (267,061)