Commitments and Contingencies, Liquidity Option Agreement (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Liquidity Option Agreement [Abstract]
Liquidity option agreement	$ 293.7		$ 293.7		$ 269.6
Change in fair value of Liquidity Option Agreement	$ 18.6	$ 23.3	$ 24.1	$ 21.1
Percentage of capital stock we agreed to purchase under liquidity option agreement			100.00%
Liquidity Option exercise period			90 days
Number of units held by limited partner	54,807,352		54,807,352
Liquidity Option Agreement [Member]
Liquidity Option Agreement [Abstract]
Fair value inputs, Assumed long-term debt			$ 2,200.0
Fair value inputs, Interest rate on assumed debt of OTA following option exercise			4.50%
Increase in fair value of liquidity option agreement excluding assumption of debt	$ 224.6		$ 224.6
Fair value inputs, Life of debt assumed after Liquidity option is exercised			30 years
Fair value inputs, federal and state tax rate			38.00%
Cash flow projections discount rate			7.60%
Fair value inputs, weighted-average expected ownership percentage of contributed units at beginning of option period			87.00%
Increase in fair value of liquidity option agreement assuming retention of all units	$ 45.1		$ 45.1
Liquidity Option Agreement [Member] | Minimum [Member]
Liquidity Option Agreement [Abstract]
Fair value inputs, Expected life of OTA following option exercise			1 year
Fair value inputs, Estimated growth rates in Enterprise earnings before interest, taxes, depreciation and amortization			0.10%
Fair value inputs, OTA ownership interest in Enterprise common units			1.90%
Liquidity Option Agreement [Member] | Maximum [Member]
Liquidity Option Agreement [Abstract]
Fair value inputs, Expected life of OTA following option exercise			30 years
Fair value inputs, Estimated growth rates in Enterprise earnings before interest, taxes, depreciation and amortization			13.60%
Fair value inputs, OTA ownership interest in Enterprise common units			2.50%