Summary of Significant Accounting Policies - Premisis and Equipment (Details) |
12 Months Ended |
|---|---|
Dec. 31, 2016 | |
| Building and building improvements | Minimum | |
| Property, Plant and Equipment | |
| Property, plant and equipment, useful life | 15 years |
| Building and building improvements | Maximum | |
| Property, Plant and Equipment | |
| Property, plant and equipment, useful life | 40 years |
| Furniture, fixtures and equipment | Minimum | |
| Property, Plant and Equipment | |
| Property, plant and equipment, useful life | 3 years |
| Furniture, fixtures and equipment | Maximum | |
| Property, Plant and Equipment | |
| Property, plant and equipment, useful life | 7 years |