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Credit Facilities - Additional Information (Detail) (USD $)
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3 Months Ended | ||
|---|---|---|---|
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Mar. 31, 2013
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Jan. 31, 2013
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Dec. 31, 2012
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| Debt Disclosure [Abstract] | |||
| Line of credit, previous maximum borrowing capacity | $ 25,000,000.0 | ||
| Line of credit facility, current borrowing capacity | 10,000,000 | ||
| Interest rate description | 1-month LIBOR Daily Floating Rate plus 1.85% | ||
| Spread over LIBOR | 1.85% | ||
| Unused commitment fees | 0.25% | ||
| Outstanding borrowing under line of credit | 0 | 0 | |
| Outstanding letters of credit | $ 1,600,000 | $ 1,600,000 |