Net Income Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Number of outstanding units not included in computation of Diluted EPS (in shares)	850,000		78,000		526,000	39,000
Numerator:
Net income (loss)	$ 53,951	$ 17,734	$ 61,994	$ 35,900	$ 71,685	$ 97,894
Denominator:
Basic earnings per share weighted average shares	50,522,000		50,346,000		50,501,000	50,316,000
Dilutive effect of employee stock awards and warrants	44,000		379,000		136,000	411,000
Diluted earnings per share weighted average shares	50,566,000		50,725,000		50,637,000	50,727,000
Basic earnings per share (in dollars per share)	$ 1.07		$ 1.23		$ 1.42	$ 1.95
Diluted earnings per share (in dollars per share)	$ 1.07		$ 1.22		$ 1.42	$ 1.93
Performance shares
Number of outstanding units not included in computation of Diluted EPS (in shares)					350,000	295,000