Common Stock Common Stock (Tables)

9 Months Ended

Sep. 30, 2022

Equity [Abstract]

Share-based Payment Arrangement, Cost by Plan [Table Text Block]

The following table provides a summary of the impact of our outstanding stock-based compensation plans on the results of operations for the periods presented:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
	(in thousands)
General and administrative expense	$	6,811	$	5,479	$	18,731	$	16,420
Lease operating expense	371		300		1,221		874
Total stock-based compensation expense	$	7,182	$	5,779	$	19,952	$	17,294

Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]

The following table presents the changes in non-vested time-based RSUs to eligible employees, including executive officers, for the nine months ended September 30, 2022:

	Shares	Weighted Average Grant-Date Fair Value per Share
Non-vested at beginning of period	1,165,187	$	25.33
Granted	355,539	70.28
Vested	(545,752)	25.80
Forfeited	(41,255)	40.02
Non-vested at end of period	933,719	41.53

Restricted Stock Awards, Market-Based, Valuation assumptions [Table Text Block]

The following table summarizes the key assumptions and related information used to determine the grant-date fair value of performance stock units awarded during the periods presented:

	Nine Months Ended September 30,
	2022	2021
Expected term of award (in years)	2.9	3.0
Risk-free interest rate	1.7%	0.2%
Expected volatility	86.3%	84.6%
Weighted average grant date fair value per share	$107.85	$54.01

Schedule of Nonvested Performance-based Units Activity [Table Text Block]

The following table presents the change in non-vested market-based awards during the nine months ended September 30, 2022:

	Shares	Weighted Average Grant-Date Fair Value per Share
Non-vested at beginning of period	439,229	$	43.21
Granted	102,098	107.85
Granted for performance multiple (1)	241,183	43.10
Released (1)	(241,183)	43.10
Non-vested at end of period	541,327	55.40

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(1) Upon completion of the performance period for the PSUs granted in 2019 and a portion of the PSUs granted in 2020, a performance multiple of 190% was applied to each of the grants resulting in additional grants of PSUs in January 2022.