Share-based Compensation and Employee Benefits (Share-based Compensation - Narrative) (Details) - Restricted Stock [Member] - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Kinder Morgan, Inc. Amended and Restated Stock Compensation Plan for Nonemployee Directors[Member] \| Class P
Share-based Compensation [Abstract]
Shares of Class P common stock authorized under the plan	250,000
Kinder Morgan, Inc. Amended and Restated Stock Compensation Plan for Nonemployee Directors[Member] \| Class P \| Six Month Vesting Period [Member]
Share-based Compensation [Abstract]
Grants during the period (shares)	25,800	17,740	31,880
Value of shares granted	$ 0.5	$ 0.4	$ 0.4
Award vesting period	6 months
Kinder Morgan Inc 2015 Amended and Restated Stock Incentive Plan [Member] \| Class P
Share-based Compensation [Abstract]
Shares of Class P common stock authorized under the plan	33,000,000
Grants during the period (shares)	5,389,476	3,221,691	2,816,599
Intrinsic value of restricted stock vested	$ 42.0	$ 30.0	$ 25.0
Expense related to restricted stock awards	63.0	65.0	66.0
Amounts capitalized related to restricted stock awards	13.0	9.0	$ 9.0
Unrecognized compensation costs	$ 127.0	$ 127.0
Unrecognized compensation costs, weighted average remaining amortization period	2 years 3 months 26 days	2 years 3 months 26 days
Kinder Morgan Inc 2015 Amended and Restated Stock Incentive Plan [Member] \| Class P \| Minimum [Member]
Share-based Compensation [Abstract]
Award vesting period	1 year
Kinder Morgan Inc 2015 Amended and Restated Stock Incentive Plan [Member] \| Class P \| Maximum [Member]
Share-based Compensation [Abstract]
Award vesting period	10 years
KML Restricted Share Unit Plan for Employees [Member]
Share-based Compensation [Abstract]
Expense related to restricted stock awards	$ 6.0	$ 1.0
Amounts capitalized related to restricted stock awards	2.0	$ 1.0
Unrecognized compensation costs	$ 3.0
Unrecognized compensation costs, weighted average remaining amortization period	2 years 1 month 6 days

Represents the compensation cost capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, units, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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- Definition

The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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Intrinsic value of equity-based compensation awards vested. Excludes stock and unit options.

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