Note 8 - Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	Fair Value Measurements Using
December 31, 2014	Fair Value		Quoted Prices in Active Markets For Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and cash equivalents	$	69,767	$	69,767	$	-	$	-
Restricted cash and cash equivalents		10,651		10,651		-		-
Marketable equity securities		132,535		132,535		-		-
Corporate debt securities		68,916		39,909		29,007		-
Commercial mortgage-backed securities		63,252		-		63,252		-
U.S. Treasury securities		14,728		14,728		-		-
State and municipal securities		11,377		2,216		9,161		-
Total financial assets	$	371,226	$	269,806	$	101,420	$	-

	Fair Value Measurements Using
December 31, 2013	Fair Value		Quoted Prices in Active Markets For Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and cash equivalents	$	81,705	$	81,705	$	-	$	-
Restricted cash and cash equivalents		13,929		13,929		-		-
Marketable equity securities		105,009		105,009		-		-
Corporate debt securities		65,006		-		65,006		-
Commercial mortgage-backed securities		45,856		-		45,856		-
U.S. Treasury securities		22,841		22,841		-		-
State and municipal securities		8,300		-		8,300		-
Total financial assets	$	342,646	$	223,484	$	119,162	$	-