Note 12 - Pension and Other Postretirement Benefit Plans - Employee Pension Plan’s Assets that are Carried at Fair Value, and the Method Used to Determine Fair Value (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pooled Separate Accounts
Plan Investments		$ 20,146	$ 19,924	$ 20,509
Retirement Plan [Member]
Pooled Separate Accounts
Plan Investments		20,146
Retirement Plan [Member] | Fair Value, Inputs, Level 1 [Member]
Pooled Separate Accounts
Plan Investments			19,924
Retirement Plan [Member] | U.S. Large-Cap Growth [Member]
Pooled Separate Accounts
Plan Investments	[1]	4,702
Retirement Plan [Member] | U.S. Large-Cap Growth [Member] | Fair Value, Inputs, Level 1 [Member]
Pooled Separate Accounts
Plan Investments	[1]		5,114
Retirement Plan [Member] | U.S. Large-cap Value [Member]
Pooled Separate Accounts
Plan Investments	[2]	4,789
Retirement Plan [Member] | U.S. Large-cap Value [Member] | Fair Value, Inputs, Level 1 [Member]
Pooled Separate Accounts
Plan Investments	[2]		4,619
Retirement Plan [Member] | U.S. Small-cap Blend [Member]
Pooled Separate Accounts
Plan Investments	[3]	2,362
Retirement Plan [Member] | U.S. Small-cap Blend [Member] | Fair Value, Inputs, Level 1 [Member]
Pooled Separate Accounts
Plan Investments	[3]		2,094
Retirement Plan [Member] | International Blend [Member]
Pooled Separate Accounts
Plan Investments	[4]	2,017
Retirement Plan [Member] | International Blend [Member] | Fair Value, Inputs, Level 1 [Member]
Pooled Separate Accounts
Plan Investments	[4]		2,079
Retirement Plan [Member] | PIMCO Bond Fund [Member]
Pooled Separate Accounts
Plan Investments	[5]	5,950
Retirement Plan [Member] | PIMCO Bond Fund [Member] | Fair Value, Inputs, Level 1 [Member]
Pooled Separate Accounts
Plan Investments	[5]		5,671
Retirement Plan [Member] | Prudential Short-term [Member]
Pooled Separate Accounts
Plan Investments	[6]	$ 326
Retirement Plan [Member] | Prudential Short-term [Member] | Fair Value, Inputs, Level 1 [Member]
Pooled Separate Accounts
Plan Investments	[6]		$ 347

[1] Comprised of large-cap stocks seeking to outperform, over the long term, the Russell 1000 Growth Index. The portfolio will typically hold between 55 and 70 stocks.

[2] Comprised of large-cap stocks seeking to outperform the Russell 1000 Value benchmark over the rolling three and five year periods, or a full market cycle, whichever is longer.

[3] Comprised of stocks with market capitalization of between $100 million and the market capitalization of the largest stock in the Russell 2000 index at the time of purchase. The portfolio will typically hold between 40 and 100 stocks.

[4] Comprised of non-U.S. domiciled stocks. The portfolio will typically hold between 80 and 90 stocks.

[5] Comprised of a portfolio of fixed income securities including U.S agency mortgage-backed securities and investment grade bonds.

[6] Comprised of money market instruments with an emphasis on safety and liquidity.