Related parties (Tables)

12 Months Ended

Dec. 31, 2012

Related Party Transactions [Abstract]

Summary of Related Party Balances and Transactions

The following table summarizes these related party balances and transactions as of and for the years ended December 31, 2012, 2011 and 2010.

	Year Ended December 31,
(U.S. Dollars, in thousands)	2012		2011		2010
Sales	$	—	$	479	$	3,081
Purchases		—		—		4,911
Accounts payable		—		—		334
Accounts receivable		—		106		676