Commitments and Contingencies, Liquidity Option Agreement (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Oct. 02, 2014
Liquidity Option Agreement [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Probability weighted discounted cash flows	119.4
Liquidity Option Agreement [Member] | 50% Probability [Member] | M&B exercises option; OTA owns 100% of units
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Number of units held by limited partner (in units)	54,800,000
Discounted cash flows	164.7
Probability weighted discounted cash flows	82.4
Liquidity Option Agreement [Member] | 20% Probability [Member] | M&B exercises option; OTA owns 75% of units
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Number of units held by limited partner (in units)	41,100,000
Discounted cash flows	123.5
Probability weighted discounted cash flows	24.7
Liquidity Option Agreement [Member] | 10% Probability [Member] | M&B exercises option; OTA owns 50% of units
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Number of units held by limited partner (in units)	27,400,000
Discounted cash flows	82.4
Probability weighted discounted cash flows	8.2
Liquidity Option Agreement [Member] | 10% Probability [Member] | M&B exercises option; OTA owns 25% of units
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Number of units held by limited partner (in units)	13,700,000
Discounted cash flows	41.2
Probability weighted discounted cash flows	4.1
Liquidity Option Agreement [Member] | 10% Probability [Member] | M&B does not exercise option
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Number of units held by limited partner (in units)	0
Discounted cash flows	0
Probability weighted discounted cash flows	0
Level 3 [Member] | Liquidity Option Agreement [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, Expected life of OTA following option exercise (in years)	30
Fair value inputs, Interest rate on assumed debt of OTA following option exercise	4.9% over 30 years
Fair value inputs, federal and state tax rate (in hundredths)	38.00%
Cash flow projections discount rate (in hundredths)	7.40%
Liquidity Option Agreement [Abstract]
Liquidity Option Agreement	119.4
Level 3 [Member] | Liquidity Option Agreement [Member] | Maximum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, Estimated growth rates in Enterprise earnings before interest, taxes, depreciation and amortization (in hundredths)	14.00%
Fair value inputs, OTA ownership interest in Enterprise common units (in hundredths)	2.80%
Fair value inputs, Forecasted yield on Enterprise common units (in hundredths)	5.50%
Level 3 [Member] | Liquidity Option Agreement [Member] | Minimum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Fair value inputs, Estimated growth rates in Enterprise earnings before interest, taxes, depreciation and amortization (in hundredths)	3.00%
Fair value inputs, OTA ownership interest in Enterprise common units (in hundredths)	1.90%
Fair value inputs, Forecasted yield on Enterprise common units (in hundredths)	4.00%
Oiltanking Partners L.P. - Step 1 [Member]
Business Acquisition [Line Items]
Common units issued in connection with acquisition (in units)	54,807,352
Liquidity Option Agreement [Abstract]
Liquidity Option Agreement		$ 119.4
Oiltanking Partners L.P. - Step 1 [Member] | Maximum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Cash flow projections discount rate (in hundredths)	8.50%
Oiltanking Partners L.P. - Step 1 [Member] | Minimum [Member]
Fair Value Measurements, Recurring, Valuation Techniques [Line Items]
Cash flow projections discount rate (in hundredths)	5.50%