Fan Pier Leases	12 Months Ended
Dec. 31, 2012
Fan Pier Leases [Abstract]
Fan Pier Leases	Fan Pier Leases In the second quarter of 2011, the Company entered into two leases, pursuant to which the Company agreed to lease approximately 1.1 million square feet of office and laboratory space in two buildings (the "Buildings") that the landlord is building at Fan Pier in Boston, Massachusetts (the “Fan Pier Leases”). The Company expects to commence lease payments in December 2013 and to make payments for the period ending 15 years from the commencement date. The Company has an option to extend the term of the Fan Pier Leases for an additional ten years. Because the Company is involved in the construction project, including having responsibility to pay for a portion of the costs of finish work and structural elements of the Buildings, the Company is deemed for accounting purposes to be the owner of the Buildings during the construction period. Accordingly, the Company has recorded project construction costs incurred by the landlord as an asset and a related financing obligation in “Property and equipment, net” and “Construction financing lease obligation,” respectively, on the Company’s consolidated balance sheets. The Company bifurcates its future lease payments pursuant to the Fan Pier Leases into (i) a portion that is allocated to the Buildings and (ii) a portion that is allocated to the land on which the Buildings are being constructed, which is recorded as rental expense. Although the Company will not begin making lease payments pursuant to the Fan Pier Leases until the commencement date, the portion of the lease obligations allocated to the land is treated for accounting purposes as an operating lease that commenced in the second quarter of 2011. Once the landlord completes the construction of the Buildings, the Company will evaluate the Fan Pier Leases in order to determine whether or not the Fan Pier Leases meet the criteria for “sale-leaseback” treatment. If the Fan Pier Leases meet the “sale-leaseback” criteria, the Company will remove the asset and the related liability from its consolidated balance sheet and treat the Fan Pier Leases as either operating or capital leases based on the Company’s assessment of the accounting guidance. The Company expects that upon completion of construction of the Buildings the Fan Pier Leases will not meet the “sale-leaseback” criteria. If the Fan Pier Leases do not meet “sale-leaseback” criteria, the Company will treat the Fan Pier Leases as a financing obligation and will depreciate the asset over its estimated useful life.

Fan Pier Leases

In the second quarter of 2011, the Company entered into two leases, pursuant to which the Company agreed to lease approximately 1.1 million square feet of office and laboratory space in two buildings (the "Buildings") that the landlord is building at Fan Pier in Boston, Massachusetts (the “Fan Pier Leases”). The Company expects to commence lease payments in December 2013 and to make payments for the period ending 15 years from the commencement date. The Company has an option to extend the term of the Fan Pier Leases for an additional ten years.

Because the Company is involved in the construction project, including having responsibility to pay for a portion of the costs of finish work and structural elements of the Buildings, the Company is deemed for accounting purposes to be the owner of the Buildings during the construction period. Accordingly, the Company has recorded project construction costs incurred by the landlord as an asset and a related financing obligation in “Property and equipment, net” and “Construction financing lease obligation,” respectively, on the Company’s consolidated balance sheets. The Company bifurcates its future lease payments pursuant to the Fan Pier Leases into (i) a portion that is allocated to the Buildings and (ii) a portion that is allocated to the land on which the Buildings are being constructed, which is recorded as rental expense. Although the Company will not begin making lease payments pursuant to the Fan Pier Leases until the commencement date, the portion of the lease obligations allocated to the land is treated for accounting purposes as an operating lease that commenced in the second quarter of 2011.

Once the landlord completes the construction of the Buildings, the Company will evaluate the Fan Pier Leases in order to determine whether or not the Fan Pier Leases meet the criteria for “sale-leaseback” treatment. If the Fan Pier Leases meet the “sale-leaseback” criteria, the Company will remove the asset and the related liability from its consolidated balance sheet and treat the Fan Pier Leases as either operating or capital leases based on the Company’s assessment of the accounting guidance. The Company expects that upon completion of construction of the Buildings the Fan Pier Leases will not meet the “sale-leaseback” criteria. If the Fan Pier Leases do not meet “sale-leaseback” criteria, the Company will treat the Fan Pier Leases as a financing obligation and will depreciate the asset over its estimated useful life.