Acquisitions and Divestitures - Balance Sheet (Details) - USD ($) $ in Millions		Sep. 30, 2017		Dec. 31, 2016		Sep. 30, 2016		Dec. 31, 2015
Current assets
Cash and cash equivalents		$ 171.9	[1]	$ 121.9	[1],[2]	$ 160.8	[3]	$ 93.0	[3]
Accounts receivable – third parties, net		12.9		20.8	[2]
Accounts receivable – related parties		16.2		12.1	[2]
Allowance oil		10.7		11.7	[2]
Prepaid expenses		1.2		6.5	[2]
Total current assets		212.9		173.0	[2]
Equity method investments		253.8		262.4	[2]
Property, plant and equipment, net		608.9		610.6	[2]
Cost investments		39.8		39.8	[2]
Other assets		1.3		0.6	[2]
Total assets		1,116.7		1,086.4	[2]
Current liabilities
Accounts payable – third parties		2.5		4.1	[2]
Accounts payable – related parties		10.5		5.4	[2]
Deferred revenue – third parties		6.5		6.0	[2]
Deferred revenue – related parties		20.8		7.9	[2]
Accrued liabilities – third parties		17.2		6.9	[2]
Accrued liabilities – related parties		5.9		5.1	[2]
Total current liabilities		63.4		35.4	[2]
Noncurrent liabilities
Debt payable – related party		1,000.6		686.0	[2]
Lease liability – related party		24.4		24.9	[2]
Asset retirement obligations		1.4		1.4	[2]
Other unearned income		2.7		2.1	[2]
Total noncurrent liabilities		1,029.1		714.4	[2]
Total liabilities		1,092.5		749.8	[2]
Commitments and Contingencies (Note 11)					[2]
EQUITY
Total partners' capital		3.4		98.3	[2]
Noncontrolling interest		20.8		21.6	[2]
Net parent investment		0.0		216.7	[2]
Total equity	[4]	24.2		336.6	[2]
Total liabilities and equity		1,116.7		1,086.4	[2]
Shell Pipeline Company L P
EQUITY
General partner unitholders		(2,256.8)		(1,873.7)	[2]
Common Units | General Public
EQUITY
Limited partner unitholders		2,770.4		2,485.7	[2]
Common Units | Shell Pipeline Company L P
EQUITY
Limited partner unitholders		(510.2)		(124.1)	[2]
Subordinated Units | Shell Pipeline Company L P
EQUITY
Limited partner unitholders		0.0		(389.6)	[2]
Total equity		$ 0.0		(389.6)
Previously Reported
Current assets
Cash and cash equivalents				121.9		160.8		93.0
Accounts receivable – third parties, net				18.4
Accounts receivable – related parties				10.1
Allowance oil				9.0
Prepaid expenses				6.0
Total current assets				165.4
Equity method investments				262.4
Property, plant and equipment, net				398.0
Cost investments				39.8
Other assets				0.0
Total assets				865.6
Current liabilities
Accounts payable – third parties				1.5
Accounts payable – related parties				5.2
Deferred revenue – third parties				6.0
Deferred revenue – related parties				7.9
Accrued liabilities – third parties				5.6
Accrued liabilities – related parties				5.1
Total current liabilities				31.3
Noncurrent liabilities
Debt payable – related party				686.0
Lease liability – related party				24.9
Asset retirement obligations				1.4
Other unearned income				2.1
Total noncurrent liabilities				714.4
Total liabilities				745.7
Commitments and Contingencies (Note 11)
EQUITY
Total partners' capital				98.3
Noncontrolling interest				21.6
Net parent investment				0.0
Total equity				119.9
Total liabilities and equity				865.6
Previously Reported | Shell Pipeline Company L P
EQUITY
General partner unitholders				(1,873.7)
Previously Reported | Common Units | General Public
EQUITY
Limited partner unitholders				2,485.7
Previously Reported | Common Units | Shell Pipeline Company L P
EQUITY
Limited partner unitholders				(124.1)
Previously Reported | Subordinated Units | Shell Pipeline Company L P
EQUITY
Limited partner unitholders				(389.6)
Adjustment
Current assets
Cash and cash equivalents				0.0		$ 0.0		$ 0.0
Accounts receivable – third parties, net				2.4
Accounts receivable – related parties				2.0
Allowance oil				2.7
Prepaid expenses				0.5
Total current assets				7.6
Equity method investments				0.0
Property, plant and equipment, net				212.6
Cost investments				0.0
Other assets				0.6
Total assets				220.8
Current liabilities
Accounts payable – third parties				2.6
Accounts payable – related parties				0.2
Deferred revenue – third parties				0.0
Deferred revenue – related parties				0.0
Accrued liabilities – third parties				1.3
Accrued liabilities – related parties				0.0
Total current liabilities				4.1
Noncurrent liabilities
Debt payable – related party				0.0
Lease liability – related party				0.0
Asset retirement obligations				0.0
Other unearned income				0.0
Total noncurrent liabilities				0.0
Total liabilities				4.1
Commitments and Contingencies (Note 11)
EQUITY
Total partners' capital				0.0
Noncontrolling interest				0.0
Net parent investment				216.7
Total equity				216.7
Total liabilities and equity				220.8
Adjustment | Shell Pipeline Company L P
EQUITY
General partner unitholders				0.0
Adjustment | Common Units | General Public
EQUITY
Limited partner unitholders				0.0
Adjustment | Common Units | Shell Pipeline Company L P
EQUITY
Limited partner unitholders				0.0
Adjustment | Subordinated Units | Shell Pipeline Company L P
EQUITY
Limited partner unitholders				$ 0.0

[1] The financial information for the nine months ended September 30, 2017 reflects adjustments for the acquisition of the Shell Delta,Na Kika and Refinery Gas Pipeline Operations from January 1, 2017 through May 9, 2017.

[2] Prior period financial information has been retrospectively adjusted for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations.

[3] Prior period financial information has been retrospectively adjusted for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations.

[4] Prior period financial information has been retrospectively adjusted for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations.