Acquisitions (Schedule Of Impact On Financial Statements Due To Acquisition, Statement Of Operations) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended				12 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Dec. 31, 2011	Jan. 31, 2011
Sales of natural gas, propane, NGLs and condensate	305.8		$ 496.1	[1]	$ 1,089.4	[2]	$ 1,652.7	[3]
Transportation, processing and other	45.0		42.8	[1]	130.7	[2]	122.2	[3]
Gains from commodity derivative activity, net	(19.9)		54.7	[1]	50.1	[2]	28.2	[3]
Total operating revenues	330.9		593.6	[1]	1,270.2	[2]	1,803.1	[3]
Purchases of natural gas, propane and NGLs	268.0		449.0	[1]	973.4	[2]	1,464.3	[3]
Operating and maintenance expense	35.7		36.7	[1]	91.7	[2]	91.3	[3]
Depreciation and amortization expense	14.8		25.9	[1]	49.6	[2]	74.9	[3]
General and administrative expense	11.1		12.0	[1]	34.0	[2]	35.2	[3]
Other income	(0.1)		(0.2)	[1]	(0.4)	[2]	(0.4)	[3]
Total operating costs and expenses	329.5		523.4	[1]	1,148.3	[2]	1,665.3	[3]
Operating income	1.4		70.2	[1]	121.9	[2]	137.8	[3]
Interest expense, net	(8.1)		(8.6)	[1]	(31.8)	[2]	(25.0)	[3]
Earnings from unconsolidated affiliates	8.9		6.9	[1]	16.6	[2]	17.1	[3]
Income before income taxes	2.2		68.5	[1]	106.7	[2]	129.9	[3]
Income tax expense	(0.3)	[4]	(0.4)	[1],[4]	(1.0)	[2],[4]	(0.9)	[3],[4]
Net income	1.9		68.1	[1]	105.7	[2]	129.0	[3]
Net income attributable to noncontrolling interests	(0.6)		0.4	[1]	(2.0)	[2]	(12.8)	[3]
Net income attributable to partners	1.3		68.5	[1]	103.7	[2]	116.2	[3]
DCP Midstream Partners, LP (As Previously Reported) [Member]
Sales of natural gas, propane, NGLs and condensate			290.4	[5]			1,043.2	[5]
Transportation, processing and other			40.8	[5]			114.9	[5]
Gains from commodity derivative activity, net			52.1	[5]			24.5	[5]
Total operating revenues			383.3	[5]			1,182.6	[5]
Purchases of natural gas, propane and NGLs			257.3	[5]			906.6	[5]
Operating and maintenance expense			31.5	[5]			77.3	[5]
Depreciation and amortization expense			20.6	[5]			60.6	[5]
General and administrative expense			9.4	[5]			27.0	[5]
Other income			(0.2)	[5]			(0.4)	[5]
Total operating costs and expenses			318.6	[5]			1,071.1	[5]
Operating income			64.7	[5]			111.5	[5]
Interest expense, net			(8.6)	[5]			(25.0)	[5]
Earnings from unconsolidated affiliates			10.0	[5]			28.6	[5]
Income before income taxes			66.1	[5]			115.1	[5]
Income tax expense			(0.2)	[5]			(0.4)	[5]
Net income			65.9	[5]			114.7	[5]
Net income attributable to noncontrolling interests			0.4	[5]			(12.8)	[5]
Net income attributable to partners			66.3	[5]			101.9	[5]
Southeast Texas [Member]
Sales of natural gas, propane, NGLs and condensate			205.7	[6]			609.5	[6]
Transportation, processing and other			2.0	[6]			7.3	[6]
Gains from commodity derivative activity, net			2.6	[6]			3.7	[6]
Total operating revenues			210.3	[6]			620.5	[6]
Purchases of natural gas, propane and NGLs			191.7	[6]			557.7	[6]
Operating and maintenance expense			5.2	[6]			14.0	[6]
Depreciation and amortization expense			5.3	[6]			14.3	[6]
General and administrative expense			2.6	[6]	2.5		8.2	[6]
Total operating costs and expenses			204.8	[6]			594.2	[6]
Operating income			5.5	[6]			26.3	[6]
Income before income taxes			5.5	[6]			26.3	[6]
Income tax expense			(0.2)	[6]			(0.5)	[6]
Net income			5.3	[6]			25.8	[6]
Net income attributable to partners			5.3	[6]			25.8	[6]
Ownership interest percentage			33.33%				33.33%		33.33%	33.33%
Percentage of ownership	100.00%				100.00%		100.00%		100.00%
Remove Southeast Texas Equity Earnings [Member]
Earnings from unconsolidated affiliates			(3.1)	[7]			(11.5)	[7]
Income before income taxes			(3.1)	[7]			(11.5)	[7]
Net income			(3.1)	[7]			(11.5)	[7]
Net income attributable to partners			$ (3.1)	[7]			$ (11.5)	[7]

[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] For the three and nine months ended September 30, 2011, income tax expense relates primarily to the Texas margin tax and the Michigan business tax. The Michigan business tax was repealed in 2012; accordingly, income tax expense for the three and nine months ended September 30, 2012 relates primarily to the Texas margin tax.

[5] Amounts as previously reported with 33.33% of Southeast Texas' results presented as earnings from unconsolidated affiliates.

[6] Adjustments to present Southeast Texas on a consolidated basis at 100% ownership, including commodity derivatives.

[7] Adjustments to remove Southeast Texas equity earnings at 33.33%.