Note 9 - Pension and Other Postretirement Benefit Plans (Detail) - Components of net expense for pension and other postretirement benefit plans (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Employee Pension Plan [Member]
Interest cost	$ 207	$ 220
Amortization of unrecognized (gain) loss	306	263
Expected return on plan assets	(315)	(310)
Net expense	198	173
Outside Director Pension Plan [Member]
Service cost	21	20
Interest cost	24	28
Amortization of unrecognized (gain) loss	(9)	(7)
Amortization of past service liability (credit)	9	9
Net expense	45	50
Other Postretirement Benefit Plans [Member]
Service cost	112	100
Interest cost	55	54
Amortization of unrecognized (gain) loss	12	10
Amortization of past service liability (credit)	(20)	(21)
Net expense	$ 159	$ 143