Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income attributable to the Company	$ 40,009	$ 27,736	$ 103,253	$ 65,300
Weighted average number of shares:
Weighted average number of shares used in calculating basic net income per share	32,306	32,264	32,293	32,247
Effect of dilutive stock-based compensation plans:
Stock options	11	16	12	16
Weighted average number of shares used in calculating diluted net income per share	32,317	32,280	32,305	32,263
Average market price of common stock used for calculation of dilutive shares	$ 82.99	$ 72.30	$ 76.45	$ 66.01
Net income attributable to the Company per share:
Basic	1.24	0.86	3.20	2.02
Diluted	$ 1.24	$ 0.86	$ 3.20	$ 2.02