Consolidated Statements of Stockholders' Equity (Parentheticals) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Exercise of stock options, shares	(1,258)	(563)	(350)
Issuance of common stock, shares		2,883	4,516
Common Stock [Member]
Exercise of stock options, shares	1,314	563	348
Employee stock purchase plan sales, shares	49	89	110
Issuance of common stock, shares	11,500	7,547	4,774