Note 7 - Marketable Securities (Details) - Short-Term and Long-Term Marketable Securities (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 82,580	$ 100,362
Unrealized Gains	102	86
Unrealized Losses	(59)	(72)
Fair Value	82,623	100,376
US Government Agencies Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	16,453	21,713
Unrealized Gains	3	2
Unrealized Losses	(20)	(22)
Fair Value	16,436	21,693
Corporate Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	28,752	29,480
Unrealized Gains	21	30
Unrealized Losses	(35)	(20)
Fair Value	28,738	29,490
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,998
Fair Value	1,998
US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	30,222	44,474
Unrealized Gains	69	49
Unrealized Losses	(2)	(22)
Fair Value	30,289	44,501
Bank Time Deposits [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	5,155	4,695
Unrealized Gains	9	5
Unrealized Losses	(2)	(8)
Fair Value	$ 5,162	$ 4,692