Financial instruments Aggregate accounts receivable, net of allowance for doubtful accounts (Details) (Spain, Italy, Portugal, and Greece, USD $)	9 Months Ended		12 Months Ended
	Sep. 28, 2014		Dec. 31, 2013
Spain, Italy, Portugal, and Greece
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current and long-term accounts receivable (net of allowances of $8.9 million and $7.9 million at September 28, 2014 and December 31, 2013, respectively) in Spain, Italy, Greece and Portugal (1)	$ 87,733,000	[1]	$ 97,852,000	[1]
Percentage of total net current and long-term accounts receivable	29.40%		31.00%
Current and long term accounts receivable, allowances	8,900,000		7,900,000
Long-term portion of accounts receivable, net	$ 15,500,000		$ 17,600,000

[1] The long-term portion of accounts receivable, net at September 28, 2014 and December 31, 2013 was $15.5 million and $17.6 million, respectively.