Note 11 - Stock-Based Compensation - Outstanding and Exercisable Stock Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Options Outstanding, Number of Options (in shares)	2,313	2,346
Options Outstanding, Weighted- Average Exercise Price (in dollars per share)	$ 2,358.44	$ 2,103.20
Options Outstanding, Weighted- Average Remaining Contractual Life in Years (Year)	6 years 321 days
Options Exercisable, Number of Options (in shares)	1,922
Options Exercisable, Weighted- Average Exercise Price (in dollars per share)	$ 2,517.03
Options Exercisable, Weighted- Average Remaining Contractual Life in Years (Year)	6 years 222 days
Range One [Member]
Range of Exercise Prices, Lower Range (in dollars per share)	$ 0
Range of Exercise Prices, Upper Range (in dollars per share)	$ 11,484
Options Outstanding, Number of Options (in shares)	2,246
Options Outstanding, Weighted- Average Exercise Price (in dollars per share)	$ 475
Options Outstanding, Weighted- Average Remaining Contractual Life in Years (Year)	7 years 21 days
Options Exercisable, Number of Options (in shares)	1,855
Options Exercisable, Weighted- Average Exercise Price (in dollars per share)	$ 569
Options Exercisable, Weighted- Average Remaining Contractual Life in Years (Year)	6 years 299 days
Range Two [Member]
Range of Exercise Prices, Lower Range (in dollars per share)	$ 11,485
Range of Exercise Prices, Upper Range (in dollars per share)	$ 22,968
Options Outstanding, Number of Options (in shares)	18
Options Outstanding, Weighted- Average Exercise Price (in dollars per share)	$ 17,869
Options Outstanding, Weighted- Average Remaining Contractual Life in Years (Year)	1 year 51 days
Options Exercisable, Number of Options (in shares)	18
Options Exercisable, Weighted- Average Exercise Price (in dollars per share)	$ 17,869
Options Exercisable, Weighted- Average Remaining Contractual Life in Years (Year)	1 year 51 days
Range Three [Member]
Range of Exercise Prices, Lower Range (in dollars per share)	$ 45,936
Range of Exercise Prices, Upper Range (in dollars per share)	$ 57,420
Options Outstanding, Number of Options (in shares)	13
Options Outstanding, Weighted- Average Exercise Price (in dollars per share)	$ 56,460
Options Outstanding, Weighted- Average Remaining Contractual Life in Years (Year)	76 days
Options Exercisable, Number of Options (in shares)	13
Options Exercisable, Weighted- Average Exercise Price (in dollars per share)	$ 56,460
Options Exercisable, Weighted- Average Remaining Contractual Life in Years (Year)	76 days
Range Four [Member]
Range of Exercise Prices, Lower Range (in dollars per share)	$ 57,421
Range of Exercise Prices, Upper Range (in dollars per share)	$ 68,904
Options Outstanding, Number of Options (in shares)	18
Options Outstanding, Weighted- Average Exercise Price (in dollars per share)	$ 60,457
Options Outstanding, Weighted- Average Remaining Contractual Life in Years (Year)	65 days
Options Exercisable, Number of Options (in shares)	18
Options Exercisable, Weighted- Average Exercise Price (in dollars per share)	$ 60,457
Options Exercisable, Weighted- Average Remaining Contractual Life in Years (Year)	65 days
Range Five [Member]
Range of Exercise Prices, Lower Range (in dollars per share)	$ 68,905
Range of Exercise Prices, Upper Range (in dollars per share)	$ 80,348
Options Outstanding, Number of Options (in shares)	7
Options Outstanding, Weighted- Average Exercise Price (in dollars per share)	$ 76,020
Options Outstanding, Weighted- Average Remaining Contractual Life in Years (Year)	1 year 240 days
Options Exercisable, Number of Options (in shares)	7
Options Exercisable, Weighted- Average Exercise Price (in dollars per share)	$ 76,020
Options Exercisable, Weighted- Average Remaining Contractual Life in Years (Year)	1 year 240 days
Range Six [Member]
Range of Exercise Prices, Lower Range (in dollars per share)	$ 91,872
Range of Exercise Prices, Upper Range (in dollars per share)	$ 103,356
Options Outstanding, Number of Options (in shares)	8
Options Outstanding, Weighted- Average Exercise Price (in dollars per share)	$ 98,442
Options Outstanding, Weighted- Average Remaining Contractual Life in Years (Year)	332 days
Options Exercisable, Number of Options (in shares)	8
Options Exercisable, Weighted- Average Exercise Price (in dollars per share)	$ 98,442
Options Exercisable, Weighted- Average Remaining Contractual Life in Years (Year)	332 days
Range Seven [Member]
Range of Exercise Prices, Lower Range (in dollars per share)	$ 103,357
Range of Exercise Prices, Upper Range (in dollars per share)	$ 114,840
Options Outstanding, Number of Options (in shares)	3
Options Outstanding, Weighted- Average Exercise Price (in dollars per share)	$ 106,001
Options Outstanding, Weighted- Average Remaining Contractual Life in Years (Year)	3 days
Options Exercisable, Number of Options (in shares)	3
Options Exercisable, Weighted- Average Exercise Price (in dollars per share)	$ 106,001
Options Exercisable, Weighted- Average Remaining Contractual Life in Years (Year)	3 days