Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Line Items]
Net income from continuing operations	$ 2,051	$ (339)	$ 45,469	$ 41,672
Loss from discontinued operations, net of tax	(956)	(659)	(1,173)	(1,133)
Net income	$ 1,095	$ (998)	$ 44,296	$ 40,539
Average common shares outstanding:
Average common shares outstanding - basic (in shares)	29,337	28,791	29,123	28,772
Additional shares for stock-based compensation plans	57	0	63	53
Average common shares outstanding - diluted (in shares)	29,394	28,791	29,186	28,825
Earnings from continuing operations per share of common stock:
Basic (in dollars per share)	$ 0.07	$ (0.01)	$ 1.56	$ 1.45
Diluted (in dollars per share)	0.07	(0.01)	1.56	1.45
Earnings (loss) per share of common stock
Basic (in dollars per share)	0.04	(0.03)	1.52	1.41
Diluted (in dollars per share)	$ 0.04	$ (0.03)	$ 1.52	$ 1.41
Antidilutive shares	1	53	2	10
Discontinued Operations, Held-for-sale [Member] | Gill Ranch [Member]
Income Statement [Line Items]
Loss from discontinued operations, net of tax	$ (956)	$ (659)	$ (1,173)	$ (1,133)
Loss from discontinued operations per share of common stock:
Basic (in dollars per share)	$ (0.03)	$ (0.02)	$ (0.04)	$ (0.04)
Diluted (in dollars per share)	$ (0.03)	$ (0.02)	$ (0.04)	$ (0.04)