Note 8 - Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2015

Fair Value Disclosures [Abstract]

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

	Fair Value Measurements Using
March 31, 2015	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	$	78,211	$	78,211	–		–
Restricted cash and cash equivalents		20,997		20,997	–		–
Marketable equity securities		134,795		134,795	–		–
Corporate debt securities		66,887		35,007		31,880	–
Commercial mortgage–backed securities		59,711	–			59,711	–
U.S. Treasury securities		16,070		16,070	–		–
State and municipal securities		10,341		2,235		8,106	–
Total financial assets	$	387,012	$	287,315	$	99,697	–

	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	–