Note 13 - Employee Benefit Plans - Performance Stock Units (Details) - Performance Shares [Member]	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Balance of shares non-vested (in shares) | shares	0
Balance of shares non-vested, weighted average grant-date price (in dollars per share) | $ / shares	$ 0
Granted (in shares) | shares	55,823
Granted (in dollars per share) | $ / shares	$ 20.48
Vested (in shares) | shares	0
Vested, weighted average grant-date price (in dollars per share) | $ / shares	$ 0
Forfeited (in shares) | shares	0
Forfeited, weighted average grant-date price (in dollars per share) | $ / shares	$ 0
Balance of shares non-vested (in shares) | shares	55,823
Balance of shares non-vested, weighted average grant-date price (in dollars per share) | $ / shares	$ 20.48