Derivative Financial Instruments - Schedule of Notional Amounts (Details) $ in Millions	Dec. 31, 2017 USD ($)
Derivative [Line Items]
Total	$ 9,038.1
Swaps
Derivative [Line Items]
Total	515.4
Futures, forwards and spot
Derivative [Line Items]
Total	3,274.5
Written options
Derivative [Line Items]
Total	2,934.2
Purchased options
Derivative [Line Items]
Total	$ 2,314.1