Composition of Accrued Liability (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
Other Liabilities Disclosure [Abstract]
Salaries and bonuses	$ 2,755	$ 2,071	$ 1,725
Clinical study costs	217	847
Accounting and legal	1,527	491	107
Other accrued liabilities	1,920	1,072	719
Accrued liabilities	$ 6,419	$ 4,481	$ 2,551

Carrying value as of the balance sheet date of obligations incurred through that date and payable for professional fees, such as for legal and accounting services received. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Carrying value as of the balance sheet date of the obligations incurred through that date and payable for employees' services provided. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from transactions not otherwise specified in the taxonomy. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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