Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income attributable to the Company	$ 9,658	$ 11,812	$ 19,699	$ 33,652
Weighted average number of shares:
Weighted average number of shares used in calculating basic net income per share	32,012	31,848	31,965	31,822
Effect of dilutive stock-based compensation plans:
Stock options	43	98	63	102
Weighted average number of shares used in calculating diluted net income per share	32,055	31,946	32,028	31,924
Average market price of common stock used for calculation of dilutive shares	$ 33.89	$ 37.20	$ 37.10	$ 36.38
Earnings per share attributable to Company shareholders:
Basic	0.30	0.37	0.62	1.06
Diluted	$ 0.30	$ 0.37	$ 0.62	$ 1.05