Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income attributable to the Company	$ 98,589	$ 132,398	$ 82,891
Weighted average number of shares:
Weighted average number of shares used in calculating basic net income per share	32,329	32,296	32,252
Effect of dilutive stock-based compensation plans:
Stock options	7	12	15
Long-term incentive plan	20	14	28
Weighted average number of shares used in calculating diluted net income per share	32,356	32,322	32,295
Average market price of common stock used for calculation of dilutive shares	$ 58.56	$ 78.13	$ 66.95
Net income per share:
Basic (in dollars per share)	3.05	4.10	2.57
Diluted (in dollars per share)	$ 3.05	$ 4.10	$ 2.57
Common stock, shares, outstanding (in shares)	32,300	32,300	32,300