CONDENSED 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, 2013	$ 324	$ 2,392,585	$ 216,140	$ 4,304,664	$ (944,627)	$ 12,091	$ 5,981,177
Balance (in shares) at Dec. 31, 2013	323,711
Increase (Decrease) in Equity
Net income (loss)				(670,659)		1,415	(669,244)
Dividends to shareholders				(59,145)			(59,145)
Redemption of subsidiary preferred stock				(1,688)			(1,688)
Repurchase of treasury shares					(250,037)		(250,037)
Other comprehensive income (loss), net of tax			(138,618)			(1,017)	(139,635)
Issuance of common shares for stock options exercised, net of surrender of unexercised stock options	$ 3	30,260					30,263
Issuance of common shares for stock options exercised (in shares)	3,036
Share-based compensation		37,157					37,157
Other	$ 1	(7,741)				(2,319)	(10,059)
Other (in shares)	1,449
Balance at the end 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)				(372,675)		381	(372,294)
Dividends to shareholders				(69,363)			(69,363)
Repurchase of treasury shares					(99,598)		(99,598)
Other comprehensive income (loss), net of tax			(125,115)			(1,461)	(126,576)
Issuance of common shares for stock options exercised, net of surrender of unexercised stock options		1,296					1,296
Issuance of common shares for stock options exercised (in shares)	141
Share-based compensation		47,863					47,863
Other	$ 3	(8,320)				2,068	(6,249)
Other (in shares)	2,189
Balance at the end 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)				(1,029,742)		135	(1,029,607)
Dividends to shareholders				(67,965)			(67,965)
Repurchase of treasury shares					(1,687)		(1,687)
Other comprehensive income (loss), net of tax			35,474			251	35,725
Issuance of common shares for stock options exercised, net of surrender of unexercised stock options		967					967
Issuance of common shares for stock options exercised (in shares)	102
Share-based compensation		32,000					32,000
Other	$ 3	(4,735)				(3,774)	(8,506)
Other (in shares)	2,970
Balance at the end of the period at Dec. 31, 2016	$ 334	$ 2,521,332	$ (12,119)	$ 2,033,427	$ (1,295,949)	$ 7,770	$ 3,254,795
Balance (in shares) at Dec. 31, 2016	333,598