Note 10 - Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Notes Tables

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

	Fair Value Measurements Using
March 31, 2018	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	$	54,962	$	54,962	$	–	$	–
Restricted cash and cash equivalents		11,778		11,778		–		–
Marketable equity securities		123,568		123,568		–		–
Corporate debt securities		66,291		43,619		22,672		–
Mortgage–backed securities		51,488		–		51,488		–
U.S. Treasury securities		20,740		20,740		–		–
State and municipal securities		24,237		–		24,237		–
Total financial assets	$	353,064	$	254,667	$	98,397	$	–

	Fair Value Measurements Using
December 31, 2017	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	$	59,118	$	59,118	$	–	$	–
Restricted cash and cash equivalents		8,303		8,303		–		–
Marketable equity securities		139,085		139,085		–		–
Corporate debt securities		65,461		43,073		22,388		–
Mortgage-backed securities		53,544		–		53,544		–
U.S. Treasury securities		21,172		21,172		–		–
State and municipal securities		26,218		–		26,218		–
Total financial assets	$	372,901	$	270,751	$	102,150	$	–