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Investment Securities - Non-Marketable Securities (Details) |  |  | 9 Months Ended |  |
--- | --- | --- | --- | --- | ---
Oct. 21, 2016 $ / shares | Oct. 19, 2016 $ / shares | Sep. 30, 2016 USD ($) $ / shares shares | Jul. 28, 2016 | Dec. 31, 2015 USD ($)
Schedule of Cost-method Investments [Line Items] |  |  |  |  |
Federal Home Loan Bank stock, par value (usd per share) | $ / shares |  |  | $ 100 |  |
Federal Home Loan Bank, dividend rate percentage |  |  |  | 8.94% |
Investments in low income housing tax credit funds |  |  | $ 2,500,000 |  | $ 2,700,000
Low income housing tax credits and other tax benefits |  |  | 223,000 |  |
Low income housing amortization expense |  |  | 177,000 |  |
Unfunded commitments for low income housing tax credit funds |  |  | $ 1,500,000 |  |
Visa Inc. Class B common stock |  |  |  |  |
Schedule of Cost-method Investments [Line Items] |  |  |  |  |
Number of shares of securities carried at cost | shares |  |  | 16,939 |  |
Carrying value of securities carried at cost |  |  | $ 0 |  |
Fair value of Class B common stock |  |  | $ 2,300,000 |  | 2,200,000
Visa Inc. | Visa Inc. Class B common stock |  |  |  |  |
Schedule of Cost-method Investments [Line Items] |  |  |  |  |
Conversion rate on common stock |  |  | 1.6483 |  |
Subsequent event |  |  |  |  |
Schedule of Cost-method Investments [Line Items] |  |  |  |  |
Special cash dividend declared on capital stock outstanding (usd per share) | $ / shares | $ 0.27 |  |  |  |
Subsequent event | Federal Home Loan Bank |  |  |  |  |
Schedule of Cost-method Investments [Line Items] |  |  |  |  |
Special cash dividend declared on capital stock outstanding (usd per share) | $ / shares |  | $ 3.41 |  |  |
Other assets |  |  |  |  |
Schedule of Cost-method Investments [Line Items] |  |  |  |  |
Federal Home Loan Bank stock |  |  | $ 10,200,000 |  | $ 8,400,000

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