Note 8 - Capital Stock and Stock-based Compensation - Stock Option and Restricted Stock Unit Activity (Details)	3 Months Ended
	Mar. 31, 2021 $ / shares shares
Opening Balance, Stock Options Outstanding (in shares) | shares	2,637,339
Options, Outstanding, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 3.51
Options, Granted in Period (in shares) | shares	0
Options, Granted in Period, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 0
Options, exercised (in shares) | shares	(310,169)
Options, exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 4.01
Options, Cancelled / Forfeited in Period (in shares) | shares	(474,309)
Options, Cancelled / Forfeited, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 4.64
Opening Balance, Stock Options Outstanding (in shares) | shares	1,852,861
Options, Outstanding, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 3.14
Restricted Stock Units (RSUs) [Member]
Restricted Stock Units Outstanding , Balance (in shares) | shares	1,560,461
Restricted Stock Units Outstanding , Grant Date Fair Value, Balance (in dollars per share) | $ / shares	$ 2.44
Restricted Stock Units, Granted in Period (in shares) | shares	714,793
Restricted Stock Units Granted , Grant Date Fair Value, Balance (in dollars per share) | $ / shares	$ 4.39
Restricted Stock Units, Vested in Period (in shares) | shares	(340,395)
Restricted Stock Units, Vested , Grant Date Fair Value, Balance (in dollars per share) | $ / shares	$ 2.73
Restricted Stock Units, Cancelled / Forfeited in Period (in shares) | shares	(11,000)
Restricted Stock Units, Cancelled/ Forfeited , Grant Date Fair Value, Balance (in dollars per share) | $ / shares	$ 4.17
Restricted Stock Units Outstanding , Balance (in shares) | shares	1,923,859
Restricted Stock Units Outstanding , Grant Date Fair Value, Balance (in dollars per share) | $ / shares	$ 3.10
Market Condition Restricted Stock Units [Member]
Restricted Stock Units Outstanding , Balance (in shares) | shares	813,031
Restricted Stock Units Outstanding , Grant Date Fair Value, Balance (in dollars per share) | $ / shares	$ 2.12
Restricted Stock Units, Granted in Period (in shares) | shares	293,509
Restricted Stock Units Granted , Grant Date Fair Value, Balance (in dollars per share) | $ / shares	$ 4.61
Restricted Stock Units, Vested in Period (in shares) | shares	0
Restricted Stock Units, Vested , Grant Date Fair Value, Balance (in dollars per share) | $ / shares	$ 0
Restricted Stock Units, Cancelled / Forfeited in Period (in shares) | shares	0
Restricted Stock Units, Cancelled/ Forfeited , Grant Date Fair Value, Balance (in dollars per share) | $ / shares	$ 0
Restricted Stock Units Outstanding , Balance (in shares) | shares	1,106,540
Restricted Stock Units Outstanding , Grant Date Fair Value, Balance (in dollars per share) | $ / shares	$ 2.78