Note 4 - Financial Instruments (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, within One Year, Adjusted Cost Basis	$ 82,593,000
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value	82,571,000
Available-for-sale Securities, Adjusted Cost Basis	156,755,000
Available-for-sale Securities, Gross Unrealized Gains	95,000
Available-for-sale Securities, Gross Unrealized Losses	246,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	156,604,000
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Adjusted Cost Basis	74,162,000
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value	74,033,000
Investment income	4,800,000		4,300,000		6,200,000
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Adjusted Cost Basis	6,199,000
Available-for-sale Securities, Gross Unrealized Gains	0
Available-for-sale Securities, Gross Unrealized Losses	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	6,199,000
US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Adjusted Cost Basis	41,167,000
Available-for-sale Securities, Gross Unrealized Gains	11,000
Available-for-sale Securities, Gross Unrealized Losses	7,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	41,171,000
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Adjusted Cost Basis	8,221,000
Available-for-sale Securities, Gross Unrealized Gains	0
Available-for-sale Securities, Gross Unrealized Losses	8,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	8,213,000
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Adjusted Cost Basis	754,000
Available-for-sale Securities, Gross Unrealized Gains	0
Available-for-sale Securities, Gross Unrealized Losses	1,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	753,000
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Adjusted Cost Basis	100,414,000
Available-for-sale Securities, Gross Unrealized Gains	84,000
Available-for-sale Securities, Gross Unrealized Losses	230,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	100,268,000
Fair Value, Measurements, Recurring [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	3,206,811,000
Fair Value, Measurements, Recurring [Member] | Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	$ 3,189,462,000	[1]	$ 2,690,752,000	[1]

[1] Included in Cash and cash equivalents in the accompanying consolidated balance sheets as of December 31, 2011 and 2010.