Note 6 - Marketable Securities (Detail) - Fair value and gross unrealized losses of the available for sale securities: (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Unrealized loss position less than 12 months, fair value	$ 6,814	$ 112,766
Unrealized loss position, less than 12 month, gross unrealized losses	2	(2)
Unrealized loss position, 12 months or greater, fair value	6,536	35,426
Unrealized loss position, 12 month or greater, gross unrealized losses	470	(272)
Unrealized loss position, total, fair value	13,350	148,192
Unrealized loss position, total, gross unrealized losses	472	(274)
US Treasury Securities [Member]
Unrealized loss position less than 12 months, fair value	1,408	88,420
Unrealized loss position, 12 months or greater, fair value		11,056
Unrealized loss position, total, fair value	1,408	99,476
Corporate Obligations [Member]
Unrealized loss position less than 12 months, fair value	5,406	24,346
Unrealized loss position, less than 12 month, gross unrealized losses	2	(2)
Unrealized loss position, 12 months or greater, fair value	6,536	24,370
Unrealized loss position, 12 month or greater, gross unrealized losses	470	(272)
Unrealized loss position, total, fair value	11,942	48,716
Unrealized loss position, total, gross unrealized losses	$ 472	$ (274)