Note 6 - Stock-Based Compensation (Detail) - Stock Options Exercisable (USD $)	3 Months Ended
	Mar. 31, 2013
Stock Options Exercisable (in Shares)	466,015
Weighted-Average Exercise Price	$ 12.06
Exercise Price Range 1 [Member]
Exercise Price	$ 6.34
Exercise Price	$ 7.45
Stock Options Exercisable (in Shares)	146,791
Weighted-Average Exercise Price	$ 6.41
Exercise Price Range 2 [Member]
Exercise Price	$ 7.46
Exercise Price	$ 10.63
Stock Options Exercisable (in Shares)	113,901
Weighted-Average Exercise Price	$ 9.53
Exercise Price Range 3 [Member]
Exercise Price	$ 10.64
Exercise Price	$ 13.87
Stock Options Exercisable (in Shares)	92,567
Weighted-Average Exercise Price	$ 11.23
Exercise Price Range 4 [Member]
Exercise Price	$ 13.88
Exercise Price	$ 26.86
Stock Options Exercisable (in Shares)	112,756
Weighted-Average Exercise Price	$ 22.64