Supplementary Information - Condensed Consolidating Financial Information (Condensed Consolidating Balance Sheet) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011		Dec. 30, 2010
ASSETS
Cash and cash equivalents	$ 8.4	[1]	$ 7.6	[1],[2]	$ 2.9	[3]	$ 6.7	[3]
Accounts receivable	140.4		214.8	[2]
Inventories	71.6		87.9	[2]
Other	50.2		43.4	[2]
Total current assets	270.6		353.7	[2]
Property, plant and equipment, net	1,673.8		1,499.4	[2]
Goodwill and intangible assets, net	292.8		299.1	[2]
Investments in unconsolidated affiliates	229.0		107.1	[2]
Other long-term assets	51.2		18.1	[2]
Total assets	2,517.4		2,277.4	[2]
Accounts payable and other current liabilities	295.7		380.5	[2]
Long-term debt	1,038.3		746.8	[2]
Other long-term liabilities	41.9		51.8	[2]
Total liabilities	1,375.9		1,179.1	[2]
Commitments and contingent liabilities				[2]
Predecessor equity			257.4	[2]
Net equity	1,123.2		649.7	[2]
Accumulated other comprehensive loss	(15.5)		(21.2)	[2]
Total partners' equity	1,107.7		885.9	[2]
Noncontrolling interests	33.8		212.4	[2]
Total equity	1,141.5		1,098.3	[2]	1,116.4		1,076.0
Total liabilities and equity	2,517.4		2,277.4	[2]
DCP Midstream Partners, LP [Member]
ASSETS
Advances receivable - consolidated subsidiaries	828.2		370.7	[2]
Investments in consolidated subsidiaries	279.5		515.2	[2]
Total assets	1,107.7		885.9	[2]
Commitments and contingent liabilities				[2]
Net equity	1,107.7		885.9	[2]
Total partners' equity	1,107.7		885.9	[2]
Total equity	1,107.7		885.9	[2]
Total liabilities and equity	1,107.7		885.9	[2]
Subsidiary Issuer [Member]
ASSETS
Cash and cash equivalents	6.5	[1]	3.6	[1],[2]	2.1	[3]	1.5	[3]
Accounts receivable	0.1
Total current assets	6.6		3.6	[2]
Advances receivable - consolidated subsidiaries	859.1		597.2	[2]
Investments in consolidated subsidiaries	465.6		679.3	[2]
Other long-term assets	7.7		5.6	[2]
Total assets	1,339.0		1,285.7	[2]
Accounts payable and other current liabilities	18.2		18.7	[2]
Long-term debt	1,038.3		746.8	[2]
Other long-term liabilities	3.0		5.0	[2]
Total liabilities	1,059.5		770.5	[2]
Commitments and contingent liabilities				[2]
Net equity	289.6		534.6	[2]
Accumulated other comprehensive loss	(10.1)		(19.4)	[2]
Total partners' equity	279.5		515.2	[2]
Total equity	279.5		515.2	[2]
Total liabilities and equity	1,339.0		1,285.7	[2]
Non-Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	1.9	[1]	6.4	[1],[2]	2.7	[3]	6.7	[3]
Accounts receivable	140.3		214.8	[2]
Inventories	71.6		87.9	[2]
Other	50.2		43.4	[2]
Total current assets	264.0		352.5	[2]
Property, plant and equipment, net	1,673.8		1,499.4	[2]
Goodwill and intangible assets, net	292.8		299.1	[2]
Investments in unconsolidated affiliates	229.0		107.1	[2]
Other long-term assets	43.5		12.5	[2]
Total assets	2,503.1		2,270.6	[2]
Accounts payable and other current liabilities	277.5		364.2	[2]
Advances payable - consolidated subsidiaries	1,687.3		967.9	[2]
Other long-term liabilities	38.9		46.8	[2]
Total liabilities	2,003.7		1,378.9	[2]
Commitments and contingent liabilities				[2]
Predecessor equity			257.4	[2]
Net equity	471.0		423.7	[2]
Accumulated other comprehensive loss	(5.4)		(1.8)	[2]
Total partners' equity	465.6		679.3	[2]
Noncontrolling interests	33.8		212.4	[2]
Total equity	499.4		891.7	[2]
Total liabilities and equity	2,503.1		2,270.6	[2]
Consolidating Adjustments [Member]
ASSETS
Cash and cash equivalents			(2.4)	[1],[2]	(1.9)	[3]	(1.5)	[3]
Total current assets			(2.4)	[2]
Advances receivable - consolidated subsidiaries	(1,687.3)		(967.9)	[2]
Investments in consolidated subsidiaries	(745.1)		(1,194.5)	[2]
Total assets	(2,432.4)		(2,164.8)	[2]
Accounts payable and other current liabilities			(2.4)	[2]
Advances payable - consolidated subsidiaries	(1,687.3)		(967.9)	[2]
Total liabilities	(1,687.3)		(970.3)	[2]
Commitments and contingent liabilities				[2]
Net equity	(745.1)		(1,194.5)	[2]
Total partners' equity	(745.1)		(1,194.5)	[2]
Total equity	(745.1)		(1,194.5)	[2]
Total liabilities and equity	$ (2,432.4)		$ (2,164.8)	[2]

[1] 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.

[2] The financial information as of December 31, 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.

[3] The financial information during 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.