Acquisition (Schedule Of Unaudited Pro Forma Information For Condensed Consolidated Statement Of Operations) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Schedule Of Condensed Consolidating Statement Of Operations [Line Items]
Total operating revenues	$ 330.9	$ 593.6	[1]	$ 1,270.2	[2]	$ 1,803.1	[3]
Net income attributable to partners	1.3	68.5	[1]	103.7	[2]	116.2	[3]
Net income attributable to predecessor operations		(2.2)		(2.6)		(14.3)
General partner unitholders interest in net income	(10.8)	(6.8)		(29.4)		(18.5)
Net income allocable to limited partners	(9.5)	59.5		71.7		83.4
DCP Midstream Partners, LP [Member]
Schedule Of Condensed Consolidating Statement Of Operations [Line Items]
Total operating revenues		593.6		1,270.2		1,803.1
Net income attributable to partners		68.5		103.7		116.2
Net income attributable to predecessor operations		(2.2)		(2.6)		(14.3)
General partner unitholders interest in net income		(6.8)		(29.4)		(18.5)
Net income allocable to limited partners		59.5		71.7		83.4
Net income per limited partner unit - basic				$ 1.37
Net income per limited partner unit - basic and diluted		$ 1.35				$ 1.93
Net income per limited partner unit - diluted				$ 1.36
Crossroads System [Member]
Schedule Of Condensed Consolidating Statement Of Operations [Line Items]
Total operating revenues	8.5	28.0		27.0	[4]	91.3
Net income attributable to partners	0.8	0.7		1.6	[4]	3.4
Net income attributable to predecessor operations					[4]
General partner unitholders interest in net income					[4]
Net income allocable to limited partners		0.7		1.6	[4]	3.4
Net income per limited partner unit - basic				$ 0.03	[4]
Net income per limited partner unit - basic and diluted		$ 0.02				$ 0.08
Net income per limited partner unit - diluted				$ 0.03	[4]
DCP Midstream Partners, LP Pro Forma [Member]
Schedule Of Condensed Consolidating Statement Of Operations [Line Items]
Total operating revenues		621.6		1,297.2		1,894.4
Net income attributable to partners		69.2		105.3		119.6
Net income attributable to predecessor operations		(2.2)		(2.6)		(14.3)
General partner unitholders interest in net income		(6.8)		(29.4)		(18.5)
Net income allocable to limited partners		$ 60.2		$ 73.3		$ 86.8
Net income per limited partner unit - basic				$ 1.40
Net income per limited partner unit - basic and diluted		$ 1.37				$ 2.01
Net income per limited partner unit - diluted				$ 1.39

[1] The financial information for the three months ended September 30, 2011 includes the results of Southeast Texas, a transfer of net assets between entities under common control that was accounted for as if the transfer occurred at the beginning of the period, and prior years are retrospectively adjusted to furnish comparative information similar to the pooling method.

[2] The financial information for the nine months ended September 30, 2012 includes the results of Southeast Texas, a transfer of net assets between entities under common control that was accounted for as if the transfer occurred at the beginning of the period, and prior years are retrospectively adjusted to furnish comparative information similar to the pooling method.

[3] The financial information for the nine months ended September 30, 2011 includes the results of Southeast Texas, a transfer of net assets between entities under common control that was accounted for as if the transfer occurred at the beginning of the period, and prior years are retrospectively adjusted to furnish comparative information similar to the pooling method.

[4] The nine months ended September 30, 2012, includes the financial results of Crossroads for the period from January 1, 2012 through July 2, 2012.