Financial Derivatives (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Credit Default Swap, Selling Protection [Member]
Derivative [Line Items]
Total net up-front payments received	$ 137.8	$ 28.9
Minimum [Member]
Derivative [Line Items]
Low Range Of Spread On Written Credit Derivatives	0.195%	0.38%
Maximum [Member]
Derivative [Line Items]
Low Range Of Spread On Written Credit Derivatives	46.287%	29.858%