Inventories: (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Raw material	$ 19,616	$ 20,808
Work in process	4,453	3,013
Finished goods	12,471	12,512
Total	$ 36,540	$ 36,333	[1]

[1] December 31, 2012 balances were derived from audited consolidated financial statements.