Common Stock Common Stock (Tables)

3 Months Ended

Mar. 31, 2021

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 March 31,
	2021		2020
	(in thousands, except per share data)
General and administrative expense	$	4,828	$	5,408
Lease operating expense	192		264
Total stock-based compensation expense	$	5,020	$	5,672

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 all employees, including executive officers, for the three months ended March 31, 2021:

	Shares	Weighted-Average Grant Date Fair Value per Share
Non-vested at beginning of period	1,150,970	$	20.14
Granted	237,719	28.75
Vested	(206,368)	29.38
Forfeited	(9,987)	13.84
Non-vested at end of period	1,172,334	20.32

The weighted-average grant date fair value of restricted stock units was $28.75 and $22.73 for the three months ended March 31, 2021 and 2020, respectively. Total compensation cost related to non-vested time-based awards and not yet recognized in our condensed consolidated statements of operations as of March 31, 2021 was $16.3 million. This cost is expected to be recognized over a weighted-average period of 1.90 years.

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

The following table presents the change in non-vested market-based awards, including SRC PSUs, during the three months ended March 31, 2021:

	Shares	Weighted-Average Grant Date Fair Value per Share
Non-vested at beginning of period	499,547	$	38.66
Granted	207,655	54.01
Non-vested at end of period	707,202	43.17