Basis of Presentation Revision of Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revision of Financial Statements [Line Items]
Operating Expenses	$ 481.3	$ 608.2	$ 2,548.1	$ 1,790.2
As reported [Member]
Revision of Financial Statements [Line Items]
Revenue from Purchased Oil and Gas		176.3		558.6
Revenues		536.7		1,636.9
Cost of Purchased Oil and Gas		175.1		561.7
Operating Expenses		637.3		1,876.8
As revised [Member]
Revision of Financial Statements [Line Items]
Revenue from Purchased Oil and Gas		147.2		472.0
Revenues		507.6		1,550.3
Cost of Purchased Oil and Gas		146.0		475.1
Operating Expenses		608.2		1,790.2
Change [Member]
Revision of Financial Statements [Line Items]
Revenue from Purchased Oil and Gas		(29.1)		(86.6)
Revenues		(29.1)		(86.6)
Cost of Purchased Oil and Gas		(29.1)		(86.6)
Operating Expenses		$ (29.1)		$ (86.6)