Note 4 - Business Combinations (Details Textual) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Oct. 01, 2015	Apr. 23, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Alphaform A.G. [Member] | Other Income [Member]
Business Combination, Bargain Purchase, Gain Recognized, Amount			$ 300
Alphaform A.G. [Member]
Payments to Acquire Businesses, Net of Cash Acquired	$ 5,000		5,032
Business Combination, Bargain Purchase, Gain Recognized, Amount			344
FineLine Prototyping, Inc. [Member] | Accrued Liabilities and Other [Member]
Business Combination, Contingent Consideration, Liability			400
FineLine Prototyping, Inc. [Member]
Payments to Acquire Businesses, Net of Cash Acquired		$ 33,900		$ 33,864
Business Acquisition, Percentage of Voting Interests Acquired		100.00%
Proceeds from Sale of Held-to-maturity Securities		$ 15,500
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High		3,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability			2,600
Business Combination, Contingent Consideration, Liability		3,000		3,000
Business Combination, Consideration Transferred		$ 36,900		36,864
Payments to Acquire Businesses, Net of Cash Acquired			5,032	$ 33,864
Business Combination, Bargain Purchase, Gain Recognized, Amount			$ 344