Long-term Debt and Obligations - Components of Borrowings, Including Current Portion (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt Disclosure [Abstract]
Landlord payable	$ 98	$ 235	$ 404
Equipment line of credit	410		1,562
Term loans payable	18,271	13,115
Long-term debt	18,779	13,350	1,966
Less: Unamortized debt discount	(566)	(591)	(79)
Current portion	(4,405)	(2,789)	(875)
Non-current portion	$ 13,808	$ 9,970	$ 1,012

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Including the current and noncurrent portions, aggregate carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Including the current and noncurrent portions, this element represents the carrying value of loans payable which were initially due after one year or beyond the operating cycle, if longer, and which are not otherwise defined in the taxonomy.

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