Note 13 - Long-term Incentive Plan - Activity Pertaining to Phantom and Restricted Common Stock Unit Awards (Details) - Long-Term Incentive Plan [Member] - Phantom and Restricted Units Holders [Member]	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Nonvested, number of units, beginning balance (in shares) | shares	998,219
Nonvested, weighted average grant date fair value, beginning balance (in dollars per share) | $ / shares	$ 5.88
Granted, number of units (in shares) | shares	578,665
Granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 1.13
Vested, number of units (in shares) | shares	382,845
Vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 4.75
Forfeited, number of units (in shares) | shares	125,696
Forfeited, weighted average grant date fair value (in dollars per share) | $ / shares	$ 4.08
Nonvested, number of units, ending balance (in shares) | shares	1,068,343
Nonvested, weighted average grant date fair value, ending balance (in dollars per share) | $ / shares	$ 3.42