Stock-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Disclosure of Share-based Compensation Arrangements by Share-based Payment Award

The following table reflects activity related to our stock-based compensation arrangements:

(In millions)	2016		2015		2014
Stock-based compensation expense	$	45	$	42	$	40
Tax benefit recognized on stock-based compensation expense	17		16		15
Cash received by MPC upon exercise of stock option awards	10		33		26
Tax benefit received for tax deductions for stock awards exercised	4		26		19

Weighted Average Assumptions Used To Value Stock Options Awards

The Black Scholes option-pricing model values used to value stock option awards granted were determined based on the following weighted average assumptions:

	2016			2015			2014
Weighted average exercise price per share	$	35.27		$	50.85		$	42.51
Expected life in years	6.2			6.0			5.8
Expected volatility	38		%	33		%	36		%
Expected dividend yield	3.0		%	2.0		%	1.9		%
Risk-free interest rate	1.4		%	1.7		%	1.8		%
Weighted average grant date fair value of stock option awards granted	$	9.84		$	13.44		$	12.69

Summary of Stock Option Award Activity

The following is a summary of our common stock option activity in 2016:

	Number of of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Terms (in years)	Aggregate Intrinsic Value (in millions)
Outstanding at December 31, 2015	8,724,631		$	27.16
Granted	1,474,177		35.27
Exercised	(637,761	)	18.78
Forfeited, canceled or expired	(29,607	)	42.91
Outstanding at December 31, 2016	9,531,440		28.93
Vested and expected to vest at December 31, 2016	9,518,269		28.90		5.4	$	205
Exercisable at December 31, 2016	7,094,204		24.90		4.3	181

Summary of Restricted Stock Award Activity

The following is a summary of restricted stock award activity of our common stock in 2016:

	Shares of Restricted Stock (“RS”)				Restricted Stock Units (“RSU”)
	Number of Shares		Weighted Average Grant Date Fair Value		Number of Units		Weighted Average Grant Date Fair Value
Outstanding at December 31, 2015	1,074,543		$	47.70	513,220		$	24.59
Granted	732,074		36.17		45,495		40.85
RS’s Vested/RSU’s Issued	(477,339	)	46.26		(197,598	)	21.62
Forfeited	(78,935	)	47.53		—		—
Outstanding at December 31, 2016	1,250,343		41.51		361,117		28.26

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity, Vested And Unvested

The following is a summary of the values related to restricted stock and restricted stock unit awards held by MPC employees and non-employee directors:

	Restricted Stock				Restricted Stock Units
	Intrinsic Value of Awards Vested During the Period (in millions)		Weighted Average Grant Date Fair Value of Awards Granted During the Period		Intrinsic Value of Awards Vested During the Period (in millions)		Weighted Average Grant Date Fair Value of Awards Granted During the Period
2016	$	17	$	36.17	$	8	$	40.85
2015	27		50.64		21		49.87
2014	28		43.82		—		42.95

Schedule of Performance Unit Awards

The following table presents a summary of the 2016 activity for performance unit awards to be settled in shares:

	Number of Units		Weighted Average Grant Date Fair Value
Outstanding at December 31, 2015	6,145,442		$	0.92
Granted	2,329,500		0.57
Exercised	(1,904,792	)	0.95
Canceled	(314,972	)	0.93
Outstanding at December 31, 2016	6,255,178		0.78

Schedule of Share-based Compensation, Performance Unit Awards, Valuation Assumptions

Performance units paying out in units have a grant date fair value calculated using a Monte Carlo valuation model, which requires the input of subjective assumptions. The following table provides a summary of these assumptions:

	2016			2015			2014
Risk-free interest rate	0.96		%	0.95		%	0.63		%
Look-back period	2.83 years			2.84 years			2.84 years
Expected volatility	34.15		%	30.38		%	38.51		%
Grant date fair value of performance units granted	$	0.57		$	0.95		$	0.85