Assets Manufactured for Internal Use (Details) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets manufactured for internal use
Cost	$ 86,527,000	$ 86,546,000
Accumulated depreciation	(52,114,000)	(49,342,000)
Net	34,413,000	37,204,000
Depreciation expense	3,300,000	3,500,000	3,600,000
Assets Manufactured for Internal Use
Assets manufactured for internal use
Cost	23,727,000	27,503,000
Accumulated depreciation	(13,948,000)	(10,526,000)
Net	9,779,000	16,977,000
Depreciable period	5 years
Depreciation expense	3,400,000	4,900,000	3,300,000
Assets Manufactured for Internal Use \| Internal use assets
Assets manufactured for internal use
Cost	21,904,000	27,503,000
Assets Manufactured for Internal Use \| Construction in process
Assets manufactured for internal use
Cost	$ 1,823,000

The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

+ References+ Details

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References+ Details

- Definition

Gross amount of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References+ Details

- Definition

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References+ Details