Fair Value Option - Additional Information (Detail) - USD ($) |
Sep. 30, 2015 |
Dec. 31, 2014 |
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|---|---|---|---|---|
| Fair Value, Option, Quantitative Disclosures [Line Items] | ||||
| Fair value of financial instruments more than one day past due | [1] | $ 318,000 | $ 4,369,000 | |
| Corporate Bonds | ||||
| Fair Value, Option, Quantitative Disclosures [Line Items] | ||||
| Fair value of financial instruments more than one day past due | 0 | 0 | ||
| Fair value of financial instruments with non-accrual status | $ 0 | 0 | ||
| Loans and Receivables | ||||
| Fair Value, Option, Quantitative Disclosures [Line Items] | ||||
| Fair value of financial instruments more than one day past due | 0 | |||
| Fair value of financial instruments with non-accrual status | $ 0 | |||
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