Note 4 - Fair Value of Financial Instruments (Details Textual) $ in Millions	Dec. 31, 2017 USD ($)
Cash Surrender Value, Fair Value Disclosure	$ 23.7
Interest Rate Swap [Member]
Derivative, Notional Amount	$ 100.0

Fair value portion of the amount that could be realized under a life insurance contract or contracts owned by the entity, commonly known as corporate-owned life insurance (COLI) or bank-owned life insurance (BOLI).

No definition available.

Name:	us-gaap_CashSurrenderValueFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant