Assets held for sale	6 Months Ended
Assets held for sale	Jun. 30, 2012
Assets held for sale [Abstract]
Assets held for sale	5. Assets held for sale During the six months ended June 30, 2012, the Company completed the sale of two buildings in Frederick, Maryland for $12.2 million. These buildings had been classified as assets held for sale. The Company realized proceeds equal to the carrying value, less cost to sell, of these buildings and there was no gain or loss on the sale.

The entire disclosure for long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. This disclosure may include property plant and equipment accounting policies and methodology, a schedule of property, plant and equipment gross, additions, deletions, transfers and other changes, depreciation, depletion and amortization expense, net, accumulated depreciation, depletion and amortization expense and useful lives, income statement disclosures, assets held for sale and public utility disclosures.

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