Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Schedule of Segment's Revenue [Table Text Block]

Below are the third-party customers that accounted for more than 10% of our segment’s revenues:

	2016		2015		2014
Oil and Natural Gas:
Sunoco Logistics Partners L.P.	24	%	19	%	14	%
Valero Energy Corporation	11	%	15	%	24	%
Drilling:
QEP Resources, Inc.	28	%	25	%	19	%
Whiting Petroleum Corp. (formerly Kodiak Oil and Gas Corp.)	18	%	7	%	9	%
Mid-Stream:
ONEOK Partners, L.P.	30	%	29	%	44	%
Koch Energy Services, LLC	11	%	9	%	2	%
Range Resources Corporation	10	%	5	%	2	%
Tenaska Resources, LLC	10	%	18	%	22	%
Laclede Group, Inc.	9	%	12	%	16	%

Schedule Of Fair Values Of The Net Liabilities [Table Text Block]

At December 31, 2016, the fair values of the net liabilities we had with each of the counterparties with respect to all of our commodity derivative transactions are listed in the table below:

	December 31, 2016
	(In millions)
Canadian Imperial Bank of Commerce	$	11.1
Bank of Montreal	8.0
Scotiabank	2.5
Total liabilities	$	21.6