CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (loss)	Treasury Stock	Noncontrolling Interest
Beginning Balance at Dec. 31, 2011	$ 1,982,783	$ 42,923	$ 380,965	$ 1,847,106	$ (159,353)	$ (131,053)	$ 2,195
Beginning Balance (in shares) at Dec. 31, 2011		42,923				2,183
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(189,102)			(190,057)			955
Cash dividends ($1.36 per share)	(55,589)			(55,589)
Other comprehensive income	27,238				27,305		(67)
Distributions to noncontrolling interest shareholders	(496)						(496)
Shares issued under compensation plans (in shares)		179				49
Shares issued under compensation plans	16,597	179	13,429			2,989
Deferred compensation (in shares)						(4)
Deferred compensation	106		(10)			116
Ending Balance at Dec. 31, 2012	1,781,537	43,102	394,384	1,601,460	(132,048)	(127,948)	2,587
Ending Balance (in shares) at Dec. 31, 2012		43,102				2,130
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	151,748			150,881			867
Cash dividends ($1.36 per share)	(55,917)			(55,917)
Other comprehensive income	20,964				21,193		(229)
Distributions to noncontrolling interest shareholders	(736)						(736)
Shares issued under compensation plans (in shares)		141				65
Shares issued under compensation plans	18,374	141	14,963			3,270
Deferred compensation (in shares)						(1)
Deferred compensation	46		(9)			55
Ending Balance at Dec. 31, 2013	1,916,016	43,243	409,338	1,696,424	(110,855)	(124,623)	2,489
Ending Balance (in shares) at Dec. 31, 2013		43,243				2,064
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	188,751			187,679			1,072
Cash dividends ($1.36 per share)	(56,258)			(56,258)
Other comprehensive income	(150,117)				(150,040)		(77)
Distributions to noncontrolling interest shareholders	(1,094)						(1,094)
Settlement of convertible notes (in shares)						(1)
Settlement of convertible notes	1		(42)			43
Settlement of note hedges associated with convertible notes (in shares)						1
Settlement of note hedges associated with convertible notes	2		79			(77)
Shares issued under compensation plans (in shares)		177				81
Shares issued under compensation plans	16,277	177	13,019			3,081
Deferred compensation (in shares)						(2)
Deferred compensation	121					121
Ending Balance at Dec. 31, 2014	$ 1,913,699	$ 43,420	$ 422,394	$ 1,827,845	$ (260,895)	$ (121,455)	$ 2,390
Ending Balance (in shares) at Dec. 31, 2014		43,420				1,981