Information for Financial Instruments on Which Fair Value Option was Elected (Parenthetical) (Detail) |
9 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2015 |
Dec. 31, 2014 |
|
| Fair Value, Option, Quantitative Disclosures [Line Items] | ||
| Loans and bonds contractual payment past due, number days | 1 day | 1 day |