Note 9 - Retirement Plans (Details) - Active Pension Plan Fair Value Measurements (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets:
Active pension plan's assets	$ 66,813	$ 58,063
Insurance General Account [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Active pension plan's assets	18,598	18,759
Insurance General Account [Member]
Assets:
Active pension plan's assets	18,598	18,759
Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Active pension plan's assets	2,319	1,959
Cash Equivalents [Member]
Assets:
Active pension plan's assets	2,319	1,959
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Active pension plan's assets	42,608	34,603
Equity Securities [Member]
Assets:
Active pension plan's assets	42,608	34,603
Fixed Income Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Active pension plan's assets	3,288	2,742
Fixed Income Securities [Member]
Assets:
Active pension plan's assets	3,288	2,742
Fair Value, Inputs, Level 2 [Member]
Assets:
Active pension plan's assets	$ 66,813	$ 58,063