CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) shares in Thousands, $ in Thousands	Mandatory Convertible Preferred Shares Preferred Stock	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, 2017		$ 368	$ 2,791,129	$ 11,185	$ 1,423,154	$ (1,314,020)	$ 26,957	$ 2,938,773
Balance (in shares) at Dec. 31, 2017		367,510
Increase (Decrease) in Equity
Net income (loss)					(342,953)		3,492	(339,461)
Dividends to common shareholders					(40,511)			(40,511)
Dividends to preferred shareholders					(3,680)			(3,680)
Common share issuance		$ 40	301,974					302,014
Common share issuance (in shares)		40,250
Convertible preferred stock issuance	$ 6		278,566					278,572
Convertible preferred stock issuance (in shares)	5,750
Other comprehensive income (loss), net of tax				(23,758)			(159)	(23,917)
Share-based compensation			14,732					14,732
Adjustment to retained earnings | Accounting Standards Update 2016-01					9,144			9,144
Adjustment to retained earnings | Accounting Standards Update 2016-16					(34,132)			(34,132)
Adjustment to retained earnings				(9,144)
Noncontrolling interest contributions (distributions)							(4,676)	(4,676)
Less: accrued distribution on redeemable noncontrolling interest in subsidiary					(4,522)			(4,522)
Other		$ 2	(3,690)					(3,688)
Other (in shares)		2,492
Balance at the end of the period at Jun. 30, 2018	$ 6	$ 410	3,382,711	(12,573)	1,006,500	(1,314,020)	25,614	3,088,648
Balance (in shares) at Jun. 30, 2018	5,750	410,252
Balance at the beginning of the period at Mar. 31, 2018		$ 370	2,797,893	(7,151)	1,232,516	(1,314,020)	27,400	2,737,008
Balance (in shares) at Mar. 31, 2018		370,320
Increase (Decrease) in Equity
Net income (loss)					(198,752)		2,953	(195,799)
Dividends to common shareholders					(21,460)			(21,460)
Dividends to preferred shareholders					(3,680)			(3,680)
Common share issuance		$ 40	301,974					302,014
Common share issuance (in shares)		40,250
Convertible preferred stock issuance	$ 6		278,566					278,572
Convertible preferred stock issuance (in shares)	5,750
Other comprehensive income (loss), net of tax				(5,422)			(63)	(5,485)
Share-based compensation			6,104					6,104
Noncontrolling interest contributions (distributions)							(4,676)	(4,676)
Less: accrued distribution on redeemable noncontrolling interest in subsidiary					(2,124)			(2,124)
Other			(1,826)					(1,826)
Other (in shares)		(318)
Balance at the end of the period at Jun. 30, 2018	$ 6	$ 410	3,382,711	(12,573)	1,006,500	(1,314,020)	25,614	3,088,648
Balance (in shares) at Jun. 30, 2018	5,750	410,252
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)
Repurchase of preferred shares			(79)					(79)
Repurchase of preferred shares (in shares)	(4)
Other comprehensive income (loss), net of tax				15,835			59	15,894
Share-based compensation			14,164					14,164
Adjustment to retained earnings								0
Noncontrolling interest contributions (distributions)							(813)	(813)
Less: 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)
Less: 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