Note 7. Employee Benefit Plans (Detail) - Net Periodic Pension Cost (Income) Three Months Ended September 30 (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Pension Benefits [Member]
Service cost	$ 970	$ 550	$ 1,939	$ 1,101
Interest cost	1,029	931	2,057	1,862
Expected return on plan assets	(1,371)	(1,260)	(2,741)	(2,520)
Amortization of prior service cost	100	150	201	301
Amortization of net (gain) loss	220	217	440	433
Net periodic benefit cost	948	588	1,896	1,177
Other Benefits [Member]
Service cost	13	12	27	23
Interest cost	20	19	39	37
Expected return on plan assets	22		22
Amortization of prior service cost	(33)	13	(22)	26
Amortization of net (gain) loss	11	(12)		(23)
Net periodic benefit cost	$ 33	$ 32	$ 66	$ 63