Business Combinations (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended				14 Months Ended
	Feb. 28, 2015	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 13, 2015
Description of Business Combinations:
Cash paid to acquire business			$ 198.7	$ 1,000.0	$ 1,056.5
Common units issued in connection with acquisition					36,827,517	54,807,352
Intangible assets reclassified to goodwill					$ 1,454.1
EFS Midstream Contract with Producers [Member]
Description of Business Combinations:
Contractual obligation			$ 270.0
Azure Midstream Partners, L.P. [Member]
Description of Business Combinations:
Business acquisition, description			The acquired business assets, which are located primarily in East Texas, include over 750 miles of natural gas gathering pipelines and two natural gas processing facilities (Panola and Fairway) with an aggregate processing capacity of 130 MMcf/d. The acquired business primarily serves production from the Haynesville Shale and Bossier, Cotton Valley and Travis Peak formations.
Total consideration for acquisition			$ 191.4
Eagle Ford Midstream Assets [Member]
Description of Business Combinations:
Business acquisition, description			The EFS Midstream System provides condensate gathering and processing services as well as gathering, treating and compression services for the associated natural gas.
Total consideration for acquisition					2,100.0
Cash paid to acquire business				$ 1,000.0	1,100.0
Revenues from acquired assets		$ 117.8
Net income from acquired assets		$ 59.9
Oiltanking Partners L.P. [Member]
Description of Business Combinations:
Business acquisition, description			Oiltanking owned marine terminals located on the Houston Ship Channel and at the Port of Beaumont featuring a number of ship and barge docks and extensive crude oil and petroleum products storage capacity.
Total consideration for acquisition						$ 4,400.0	$ 6,020.0
Noncontrolling interests acquired					1,400.0
Intangible assets reclassified to goodwill					1,450.0
Oiltanking Partners L.P. - Step 1 [Member]
Description of Business Combinations:
Common units acquired (in units)						15,899,802
Subordinated units acquired (in units)						38,899,802
Cash paid to acquire business						$ 2,210.0
Common units issued in connection with acquisition						54,807,352
Cash paid to assume notes receivable						$ 228.3
Oiltanking Partners L.P. - Step 2 [Member]
Description of Business Combinations:
Common units issued in connection with acquisition	36,827,517
Common units exchanged for each Oiltanking unit (in units)	1.3
Noncontrolling interests acquired					$ 1,400.0
Intangible assets reclassified to goodwill	$ 1,460.0