CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Common Shares	Capital in Excess of Par Value	Accumulated Other Comprehensive Income	Retained Earnings	Treasury Shares	Non-controlling Interest	Total
Balance at the beginning of the period at Dec. 31, 2014	$ 328	$ 2,452,261	$ 77,522	$ 3,573,172	$ (1,194,664)	$ 10,170	$ 4,918,789
Balance (in shares) at Dec. 31, 2014	328,196
Increase (Decrease) in Equity
Net income (loss)				123,634		(89)	123,545
Dividends to shareholders				(17,470)			(17,470)
Other comprehensive income (loss), net of tax			(62,754)			(880)	(63,634)
Issuance of common shares for stock options exercised, net of surrender of unexercised stock options		182					$ 182
Issuance of common shares for stock options exercised (in shares)	20						20,000
Share-based compensation		13,691					$ 13,691
Other	$ 2	(7,091)				(252)	(7,341)
Other (in shares)	1,341
Balance at the end of the period at Mar. 31, 2015	$ 330	2,459,043	14,768	3,679,336	(1,194,664)	8,949	4,967,762
Balance (in shares) at Mar. 31, 2015	329,557
Balance at the beginning of the period at Dec. 31, 2015	$ 331	2,493,100	(47,593)	3,131,134	(1,294,262)	11,158	4,293,868
Balance (in shares) at Dec. 31, 2015	330,526
Increase (Decrease) in Equity
Net income (loss)				(398,294)		724	(397,570)
Dividends to shareholders				(16,922)			(16,922)
Repurchase of treasury shares					(1,687)		(1,687)
Other comprehensive income (loss), net of tax			34,329			419	$ 34,748
Issuance of common shares for stock options exercised (in shares)							0
Share-based compensation		7,374					$ 7,374
Other	$ 1	(3,191)				(424)	(3,614)
Other (in shares)	1,149
Balance at the end of the period at Mar. 31, 2016	$ 332	$ 2,497,283	$ (13,264)	$ 2,715,918	$ (1,295,949)	$ 11,877	$ 3,916,197
Balance (in shares) at Mar. 31, 2016	331,675