Financial Instruments and Off-Balance Sheet Risk Interest Rate Derivatives - Notional Amounts (Details) |
Dec. 31, 2015
USD ($)
|
|---|---|
| Interest Rate Swaps Ending January 2017 [Member] | |
| Derivative [Line Items] | |
| Notional amount | $ 250,000,000 |
| Interest Rate Swaps Ending April 2017 [Member] | |
| Derivative [Line Items] | |
| Notional amount | 25,000,000 |
| Interest Rate Swaps Ending January 2018 [Member] | |
| Derivative [Line Items] | |
| Notional amount | $ 100,000,000 |