Stock Plans and Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

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

Schedule of Share-Based Compensation and Related Income Tax Benefit

Total pre-tax expense associated with share-based compensation and its related income tax benefit is shown in the table below. The year over year decrease in share-based compensation expense is primarily due to modifications to the terms of awards in the first and second quarters of 2017 (see Equity Award Modifications below).

	Fiscal Years
(Dollars in Millions)	2018		2017		2016
Share-Based Compensation Expense
Performance Units	$	28	$	49	$	17
Restricted Stock Units and Awards	6		15		11
Stock Options	13		22		7
Stock Awards for Directors	2		3		2
Employee Stock Purchase Plan	2		—		—
Total Share-based Compensation Expense	$	51	$	89	$	37
Income Tax Benefit	$	26	$	42	$	15

Schedule of Assumptions and Inputs Used to Estimate Fair Value of Performance Units

The fair value of the performance units awarded during the year ended December 2018 was calculated using a Monte-Carlo simulation model with the following weighted-average assumptions:

Weighted-average assumptions used:	2018
Annual dividend yield	1.6	%
Risk-free interest rate	2.3	%
Annualized volatility	29.1	%
Expected life (in years)	2.9

Schedule of Performance Unit Grant and Vesting Information

Performance unit grant and vesting information is summarized as follows:

	Fiscal Years
	2018		2017		2016
Weighted-average grant date fair value	$	55.57	$	49.50	$	24.17
Fair value of units vested in fiscal year ending (in millions)	$	14	$	26	$	31

Schedule of Performance Unit Activity Related to Outstanding Long-term Incentive Plans and Corresponding Fair Value

The performance unit activity related to the outstanding long-term incentive plans and corresponding fair value is summarized as follows:

	Performance Units Outstanding (in Thousands)		Weighted-Average Fair Value at Grant Date
Unvested at December 31, 2017	976		$	33.90
Granted	376		55.57
Forfeited	(43	)	43.09
Vested	(587	)	24.13
Unvested at December 31, 2018	722		$	52.58

Schedule of Restricted Stock Grant and Vesting Information

Restricted stock grant and vesting information is summarized as follows:

	Fiscal Years
	2018		2017		2016
Weighted-average grant date fair value	$	62.60	$	48.35	$	24.21
Fair value of units and awards vested during fiscal year ended (in millions)	$	9	$	8	$	14

Schedule of Outstanding Restricted Stock Units and Awards

The restricted stock activity related to the outstanding long-term incentive plans and other awards and corresponding fair value is summarized as follows:

	Restricted Stock Units and Awards Outstanding (in Thousands)		Weighted-Average Fair Value at Grant Date
Unvested at December 31, 2017	807		$	33.37
Granted	164		62.60
Forfeited	(23	)	42.12
Vested	(264	)	35.41
Unvested at December 31, 2018	684		$	39.30

Schedule of Assumptions and Inputs Used to Estimate Fair Value of Stock Options

Assumptions and inputs used to estimate fair value of stock options are summarized as follows:

	Fiscal Years
	2018			2017			2016
Weighted-average grant date fair value	$	14.65		$	12.84		$	4.68
Stock options valuation assumptions:
Annual dividend yield	1.5		%	1.5		%	3.0		%
Risk-free interest rate	2.6		%	2.2		%	1.4		%
Annualized volatility	27.0		%	27.1		%	27.3		%
Expected life (in years)	6.5			6.3			6.5
Other pricing model inputs:
Weighted-average grant-date market price of CSX stock (strike price)	$	54.19		$	49.63		$	24.13

Schedule of Stock Option Activity

The stock option activity is summarized as follows:

	Stock Options Outstanding (in Thousands)		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Life (in Years)	Aggregate Intrinsic Value (in Millions)
Outstanding at December 31, 2017	4,163		$	29.52
Granted	1,009		54.19
Forfeited	(169	)	37.18
Exercised	(330	)	24.99
Outstanding at December 31, 2018	4,673		$	34.89	7.7	$	139
Exercisable at December 31, 2018	1,268		$	24.99	6.9	$	50