CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) shares in Thousands, $ in Thousands	Mandatory Convertible Preferred Shares Preferred Stock	Common Stock	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, 2018	$ 6	$ 410	$ 3,392,937	$ (29,325)	$ 650,842	$ (1,314,020)	$ 49,476	$ 2,750,326
Balance (in shares) at Dec. 31, 2018	5,750	409,652
Increase (Decrease) in Equity
Net income (loss)					(321,273)		24,905	(296,368)
Dividends to common shareholders					(7,581)			(7,581)
Dividends to preferred shareholders					(8,625)			(8,625)
Other comprehensive income (loss), net of tax				15,835			59	15,894
Issuance of common shares for stock options exercised, net of surrender of unexercised stock options			(79)					(79)
Issuance of common shares for stock options exercised, net of surrender of unexercised stock options (in shares)	(4)
Share-based compensation			14,164					14,164
Noncontrolling interest contributions (distributions)							813	813
Accrued distribution on redeemable noncontrolling interest in subsidiary					(10,182)			(10,182)
Other		$ 6	(1,601)					(1,595)
Other (in shares)		6,630
Balance at the end of the period at Jun. 30, 2019	$ 6	$ 416	3,405,421	(13,490)	303,181	(1,314,020)	73,627	2,455,141
Balance (in shares) at Jun. 30, 2019	5,746	416,282
Balance at the beginning of the period at Mar. 31, 2019	$ 6	$ 416	3,400,110	(19,987)	519,810	(1,314,020)	63,704	2,650,039
Balance (in shares) at Mar. 31, 2019	5,750	415,916
Increase (Decrease) in Equity
Net income (loss)					(203,564)		10,729	(192,835)
Dividends to common shareholders					(3,634)			(3,634)
Dividends to preferred shareholders					(4,312)			(4,312)
Repurchase of preferred shares			(79)					(79)
Repurchase of preferred shares (in shares)	(4)
Other comprehensive income (loss), net of tax				6,497			7	6,504
Share-based compensation			5,740					5,740
Noncontrolling interest contributions (distributions)							(813)	(813)
Accrued distribution on redeemable noncontrolling interest in subsidiary					(5,119)			(5,119)
Other			(350)					(350)
Other (in shares)		366
Balance at the end of the period at Jun. 30, 2019	$ 6	$ 416	3,405,421	(13,490)	303,181	(1,314,020)	73,627	2,455,141
Balance (in shares) at Jun. 30, 2019	5,746	416,282
Balance at the beginning of the period at Dec. 31, 2019	$ 6	$ 416	3,412,972	(11,788)	(104,775)	(1,314,020)	67,354	2,050,165
Balance (in shares) at Dec. 31, 2019	5,613	416,198
Increase (Decrease) in Equity
Net income (loss)					(539,939)		27,632	(512,307)
Dividends to common shareholders					(3,633)			(3,633)
Dividends to preferred shareholders					(7,305)			(7,305)
Repurchase of preferred shares	$ (1)		(12,127)			(1,731)		(13,859)
Repurchase of preferred shares (in shares)	(743)
Other comprehensive income (loss), net of tax				(10,400)				(10,400)
Share-based compensation			15,757					15,757
Noncontrolling interest contributions (distributions)							1,004	1,004
Accrued distribution on redeemable noncontrolling interest in subsidiary					(8,739)			(8,739)
Other		$ 3	(1,549)				357	(1,189)
Other (in shares)		(407,809)
Balance at the end of the period at Jun. 30, 2020	$ 5	$ 419	3,415,053	(22,188)	(664,391)	(1,315,751)	94,339	1,507,486
Balance (in shares) at Jun. 30, 2020	4,870	8,389
Balance at the beginning of the period at Mar. 31, 2020	$ 5	$ 419	3,408,454	(29,006)	(508,200)	(1,315,751)	85,177	1,641,098
Balance (in shares) at Mar. 31, 2020	4,870	419,466
Increase (Decrease) in Equity
Net income (loss)					(148,112)		10,167	(137,945)
Dividends to common shareholders					(119)			(119)
Dividends to preferred shareholders					(3,653)			(3,653)
Other comprehensive income (loss), net of tax				6,818				6,818
Accrued distribution on redeemable noncontrolling interest in subsidiary					(4,307)			(4,307)
Other			6,599				(1,005)	5,594
Other (in shares)		(411,077)
Balance at the end of the period at Jun. 30, 2020	$ 5	$ 419	$ 3,415,053	$ (22,188)	$ (664,391)	$ (1,315,751)	$ 94,339	$ 1,507,486
Balance (in shares) at Jun. 30, 2020	4,870	8,389