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Derivative Instruments and Hedging Activities - Balance Sheet Offsetting Disclosure (Detail) (USD $) In Thousands, unless otherwise specified | Sep. 30, 2013 | Dec. 31, 2012
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Offsetting [Abstract] |  |
Gross Amount of Recognized Assets | $ 32 |
Gross Amount Offset in the Statement of Financial Position, Derivative Assets |  |
Net Amount of Assets Presented in the Statement of Financial Position | 32 |
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments, Derivative Assets | 32 |
Gross Amounts Not Offset in the Statement of Financial Position, Cash Collateral Received, Derivative Assets |  |
Derivative Assets, Net Amount |  |
Gross Amount of Recognized Liabilities | 44 | 353
Gross Amount Offset in the Statement of Financial Position, Derivative Liabilities |  |
Net Amount of Liabilities Presented in the Statement of Financial Position | 44 | 353
Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments, Derivative Liabilities | 44 | 353
Gross Amounts Not Offset in the Statement of Financial Position, Cash Collateral Received, Derivative Liabilities |  |
Derivative liabilities, Net Amount |  |

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