Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to the Company	$ 13,069	$ 9,658	$ 36,937	$ 19,699
Weighted average number of shares:
Weighted average number of shares used in calculating basic net income per share	32,104	32,012	32,079	31,965
Effect of dilutive stock-based compensation plans:
Stock options	37	43	39	63
Weighted average number of shares used in calculating diluted net income per share	32,141	32,055	32,118	32,028
Average market price of common stock used for calculation of dilutive shares	$ 42.03	$ 33.89	$ 38.97	$ 37.10
Earnings per share attributable to Company shareholders:
Basic	0.41	0.30	1.15	0.62
Diluted	$ 0.41	$ 0.30	$ 1.15	$ 0.62