Note 6 - Stockholders' Equity (Detail) - Summary of Outstanding and Exercisable Options (USD $)							12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 One [Member] Minimum [Member]	Dec. 31, 2012 One [Member] Maximum [Member]	Dec. 31, 2012 One [Member]	Dec. 31, 2012 Two [Member] Minimum [Member]	Dec. 31, 2012 Two [Member] Maximum [Member]	Dec. 31, 2012 Two [Member]	Dec. 31, 2012 Three [Member] Minimum [Member]	Dec. 31, 2012 Three [Member] Maximum [Member]	Dec. 31, 2012 Three [Member]	Dec. 31, 2012 Four [Member] Minimum [Member]	Dec. 31, 2012 Four [Member] Maximum [Member]	Dec. 31, 2012 Four [Member]	Dec. 31, 2012 Five [Member] Minimum [Member]	Dec. 31, 2012 Five [Member] Maximum [Member]	Dec. 31, 2012 Five [Member]	Dec. 31, 2012 Six [Member] Minimum [Member]	Dec. 31, 2012 Six [Member] Maximum [Member]	Dec. 31, 2012 Six [Member]	Dec. 31, 2012 Seven [Member] Minimum [Member]	Dec. 31, 2012 Seven [Member] Maximum [Member]	Dec. 31, 2012 Seven [Member]	Dec. 31, 2012 Eight [Member] Minimum [Member]	Dec. 31, 2012 Eight [Member] Maximum [Member]	Dec. 31, 2012 Eight [Member]	Dec. 31, 2012 Nine [Member] Minimum [Member]	Dec. 31, 2012 Nine [Member] Maximum [Member]	Dec. 31, 2012 Nine [Member]	Dec. 31, 2012 Ten [Member] Minimum [Member]	Dec. 31, 2012 Ten [Member] Maximum [Member]	Dec. 31, 2012 Ten [Member]
Options Outstanding	3,813,361	4,863,239	5,835,118	7,410,914	0.76	11.32	546,691	11.44	12.43	388,118	12.52	14.90	450,417	14.94	14.97	82,757	15.03	15.03	586,548	15.14	16.41	383,861	16.51	18.29	392,703	18.63	20.30	445,551	20.41	22.85	422,592	23.03	24.84	114,123
Outstanding, Weighted Average Remaining Contractual Life							1 year 295 days			2 years 116 days			3 years			2 years 62 days			2 years 299 days			2 years 80 days			2 years 3 months			3 years 54 days			2 years 313 days			2 years 277 days
Outstanding, Weighted Average Exercise Price (in Dollars per share)	$ 15.62	$ 15.31	$ 14.61	$ 13.48			$ 8.52			$ 12.37			$ 14.17			$ 14.93			$ 15.03			$ 15.53			$ 17.68			$ 19.70			$ 21.85			$ 24.18
Number of Options Exerciseable	3,603,762						522,609			382,792			386,542			81,635			585,480			359,242			373,249			410,922			393,194			108,097
Exercisable, Weighted Average Exercise Price (in Dollars per share)							$ 8.41			$ 12.37			$ 14.25			$ 14.93			$ 15.03			$ 15.53			$ 17.72			$ 19.72			$ 21.87			$ 24.24