Overview (Details)	12 Months Ended
	Dec. 31, 2015 Pipelines in mi shares bbl MMcf	Sep. 30, 2015
Crude Transportation [Member]
Schedule Of Overview [Line Items]
Trucks	270
Trailers	270
Crude Transportation [Member] | Wattenberg Oil Trunkline LLC [Member]
Schedule Of Overview [Line Items]
Length of pipeline network (in miles) | mi	75
Oil storage capacity, barrels	360,000
Width of Pipeline | in	12
Pipeline capacity	85,000
Crude Transportation [Member] | Maurepas Pipeline [Member]
Schedule Of Overview [Line Items]
Number of pipelines | Pipelines	3
SemGas [Member]
Schedule Of Overview [Line Items]
Gas processing plants	4
Gas plant operating capacity | MMcf	595
SemCAMS [Member]
Schedule Of Overview [Line Items]
Gas processing plants	4
Gas plant operating capacity | MMcf	695
SemLogistics [Member]
Schedule Of Overview [Line Items]
Oil storage capacity, barrels	8,700,000
SemMexico [Member]
Schedule Of Overview [Line Items]
Asphalt cement terminals and modification facilities	11
Marine terminals	2
White Cliffs Pipeline, LLC [Member]
Schedule Of Overview [Line Items]
Width of Pipeline | in	12
Equity method investment, ownership percentage	51.00%
White Cliffs Pipeline, LLC [Member] | Crude Transportation [Member]
Schedule Of Overview [Line Items]
Length of pipeline network (in miles) | mi	527
Width of Pipeline | in	12
Number of pipelines | Pipelines	2
Equity method investment, ownership percentage	51.00%
Glass Mountain Pipeline LLC [Member] | Crude Transportation [Member]
Schedule Of Overview [Line Items]
Length of pipeline network (in miles) | mi	210
Equity method investment, ownership percentage	50.00%
Ngl Energy Partners Lp [Member] | General Partner [Member] | SemStream [Member]
Schedule Of Overview [Line Items]
Equity method investment, ownership percentage	11.78%
Partnership Interest [Member] | Glass Mountain Pipeline LLC [Member]
Schedule Of Overview [Line Items]
Equity method investment, ownership percentage	50.00%
Partnership Interest [Member] | Ngl Energy Partners Lp [Member] | Limited Partner [Member] | SemStream [Member]
Schedule Of Overview [Line Items]
Equity method investment, ownership percentage	4.40%	4.40%
Investments in and Advances to Affiliates, Balance, Shares | shares	4,652,568
Kansas and Oklahoma [Member] | Crude Transportation [Member]
Schedule Of Overview [Line Items]
Length of pipeline network (in miles) | mi	570
Oil storage capacity, barrels	650,000
COLORADO | Crude Transportation [Member] | Wattenberg Oil Trunkline LLC [Member]
Schedule Of Overview [Line Items]
Length of pipeline network (in miles) | mi	16
COLORADO | Crude Facilities [Member]
Schedule Of Overview [Line Items]
Oil storage capacity, barrels	350,000
Number of Lanes in Crude Oil Truck Unloading Facility	30
OKLAHOMA | Crude Facilities [Member]
Schedule Of Overview [Line Items]
Oil storage capacity, barrels	7,600,000
Crude oil storage capacity leased to customers	6,500,000
Crude oil storage capacity used for operations	1,100,000
NORTH DAKOTA | Crude Supply and Logistics [Member]
Schedule Of Overview [Line Items]
Oil storage capacity, barrels	61,800