Stockholder's Equity (Tables)

12 Months Ended

Dec. 31, 2020

Stockholders' Equity Note [Abstract]

Common stock activity

The following summarizes Common Stock activity for each of the years ended December 31, 2018, 2019 and 2020 (in thousands):

	Common Shares
	Issued	Treasury	Outstanding
Balance at December 31, 2017	578,828	(351)	578,477
Common Stock Issued Under Stock-Based Compensation Plans	1,580	—	1,580
Treasury Stock Purchased (1)	—	(539)	(539)
Common Stock Issued Under Employee Stock Purchase Plan	—	180	180
Treasury Stock Issued Under Stock-Based Compensation Plans	—	325	325
Balance at December 31, 2018	580,408	(385)	580,023
Common Stock Issued Under Stock-Based Compensation Plans	1,688	—	1,688
Treasury Stock Purchased (1)	—	(310)	(310)
Common Stock Issued Under Employee Stock Purchase Plan	117	106	223
Treasury Stock Issued Under Stock-Based Compensation Plans	—	290	290
Balance at December 31, 2019	582,213	(299)	581,914
Common Stock Issued Under Stock-Based Compensation Plans	1,482	—	1,482
Treasury Stock Purchased (1)	—	(389)	(389)
Common Stock Issued Under Employee Stock Purchase Plan	—	377	377
Treasury Stock Issued Under Stock-Based Compensation Plans	—	187	187
Balance at December 31, 2020	583,695	(124)	583,571

(1)    Represents shares that were withheld by or returned to EOG (i) in satisfaction of tax withholding obligations that arose upon the exercise of employee stock options or SARs or the vesting of restricted stock, restricted stock unit or performance unit grants or (ii) in payment of the exercise price of employee stock options.