Earnings (Loss) Per Common Share (EPS) - Basic EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share, Basic and Diluted [Abstract]
Net income (loss)	$ 11,967	$ 4,916	$ 10,958	$ (3,009)	$ (19,058)	$ (3,154)	$ 27,841	$ (25,221)
Average common shares outstanding (in shares)	56,302			55,505			56,033	55,386
Basic EPS (in dollars per share)	$ 0.21			$ (0.05)			$ 0.50	$ (0.46)