Inventories: (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Inventory Disclosure [Abstract]
Raw material	$ 20,651	$ 25,227
Work in process	3,526	2,901
Finished goods	12,358	12,295
Total	$ 36,535	$ 40,423	[1]

[1] December 31, 2011 balances were derived from audited consolidated financial statements.