Note 6 - Marketable Securities (Detail) - Fair Value and Gross Unrealized Losses of the Available for Sale Securities: (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Less than 12 months fair value	$ 112,766
Less than 12 months gross unrealized losses	(2)
12 months or greater fair value	35,426
12 month or greater gross unrealized losses	(272)
Fair value	148,192
Gross unrealized losses	(274)
US Treasury Securities [Member]
Less than 12 months fair value	88,420	15,186
Less than 12 months gross unrealized losses		(3)
12 months or greater fair value	11,056
Fair value	99,476	15,186
Gross unrealized losses		(3)
Corporate Debt Securities [Member]
Less than 12 months fair value	24,346
Less than 12 months gross unrealized losses	(2)
12 months or greater fair value	24,370
12 month or greater gross unrealized losses	(272)
Fair value	48,716
Gross unrealized losses	$ (274)