Earnings Per Share - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Line Items]
Net income from continuing operations	$ (18,677)	$ (18,506)	$ 24,467	$ 26,963
Loss from discontinued operations, net of tax	765	(795)	267	(1,968)
Net income	$ (17,912)	$ (19,301)	$ 24,734	$ 24,995
Average common shares outstanding:
Average common shares outstanding - basic (in shares)	30,555	30,429	30,528	29,563
Additional shares for stock-based compensation plans	0	0	47	65
Average common shares outstanding - diluted (in shares)	30,555	30,429	30,575	29,628
Earnings from continuing operations per share of common stock:
Basic (in dollars per share)	$ (0.61)	$ (0.61)	$ 0.80	$ 0.91
Diluted (in dollars per share)	(0.61)	(0.61)	0.80	0.91
Loss from discontinued operations per share of common stock:
Basic (in dollars per share)	0.02	(0.02)	0.01	(0.07)
Diluted (in dollars per share)	0.02	(0.02)	0.01	(0.07)
Earnings (loss) per share of common stock
Basic (in dollars per share)	(0.59)	(0.63)	0.81	0.84
Diluted (in dollars per share)	$ (0.59)	$ (0.63)	$ 0.81	$ 0.84
Antidilutive shares	47	69	1	1
Discontinued Operations, Held-for-sale [Member] | Gill Ranch [Member]
Income Statement [Line Items]
Loss from discontinued operations, net of tax	$ 765	$ (795)	$ 267	$ (1,968)
Loss from discontinued operations per share of common stock:
Basic (in dollars per share)	$ 0.02	$ (0.02)	$ 0.01	$ (0.07)
Diluted (in dollars per share)	$ 0.02	$ (0.02)	$ 0.01	$ (0.07)