Incentive Plans (Tables)

9 Months Ended

Sep. 30, 2020

Compensation Related Costs [Abstract]

Schedule of stock-based compensation expense

Stock-based compensation expense is as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
	(in millions)
Restricted stock - Equity Awards	$	15	$	14	$	37	$	65
Restricted stock - Liability Awards (a)	4		2		7		14
Performance unit awards	6		5		15		15
Employee stock purchase plan	—		—		2		1
	$	25	$	21	$	61	$	95

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(a)Liability Awards are expected to be settled on their vesting date in cash. As of September 30, 2020 and December 31, 2019, accounts payable – due to affiliates included $5 million and $11 million, respectively, of liabilities attributable to Liability Awards.

Schedule of share based incentive award activity

Activity for restricted stock awards, performance units and stock options is as follows:

	Nine Months Ended September 30, 2020
	Restricted Stock Equity Awards	Restricted Stock Liability Awards	Performance Units	Stock Options
Beginning incentive compensation awards	824,193	246,851	116,215	121,953
Awards granted	383,771	135,176	132,621	—
Awards forfeited	(12,438)	(5,257)	—	—
Awards vested (a)	(319,203)	(102,588)	(4,735)	—
Options exercised	—	—	—	(7,728)
Ending incentive compensation awards	876,323	274,182	244,101	114,225

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(a)Per the terms of award agreements and elections, the issuance of common stock may be deferred for certain restricted stock equity awards, performance units and stock options that vest during the period.