Fair Value Disclosures - Narrative (Details) - USD ($) $ in Millions |
Dec. 31, 2015 |
Dec. 31, 2014 |
|---|---|---|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Derivative Credit Risk Valuation Adjustment, Derivative Assets | $ 0.2 | $ 0.2 |
| Level 3 [Member] | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Assets and Liabilities, Fair Value Disclosure | $ 6,100.0 | $ 5,500.0 |
| Fair Value, Assets and Liabilities Fair Value as Percent of Total Assets | 39.00% | 38.00% |
| Fair Value, Assets and Liabilities, Fair Value as Percent of Total Financial Instruments Measured at Fair Value | 69.00% | 73.00% |