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 (Accumulated Deficit)	Treasury Shares	Non-controlling Interest	Total
Balance at the beginning 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
Increase (Decrease) in Equity
Net income (loss)					(546,811)		6,178	(540,633)
Dividends declared to common shareholders					(68,612)			(68,612)
Repurchase of treasury shares						(18,071)		(18,071)
Other comprehensive income (loss), net of tax				23,304			282	23,586
Issuance of common shares for stock options exercised, net of surrender of unexercised stock options		$ 1	(10,736)					(10,735)
Issuance of common shares for stock options exercised, net of surrender of unexercised stock options (in shares)		842
Equity component of exchangeable debt			116,195					116,195
Capped call transactions			(40,250)					(40,250)
Adoption of ASU No. 2016-09			1,943		5,150			7,093
Share-based compensation			31,896					31,896
Issuance to Tesco shareholders		$ 32	178,961					178,993
Issuance to Tesco shareholders (in shares)		32,078
Noncontrolling interest contributions (distributions)							13,018	13,018
Other		$ 1	(8,212)				(291)	(8,502)
Other (in shares)		992
Balance at the end 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)					(640,948)		28,222	(612,726)
Dividends declared to common shareholders					(82,973)			(82,973)
Dividends declared to preferred shareholders					(12,305)			(12,305)
Common share issuance		$ 40	301,363					301,403
Common share issuance (in shares)		40,250
Convertible preferred share issuance	$ 6		277,921					277,927
Convertible preferred share issuance (in shares)	5,750
Other comprehensive income (loss), net of tax				(40,510)			(251)	(40,761)
Share-based compensation			26,396					26,396
Adjustment to retained earnings | Accounting Standards Update 2016-01				(9,144)	9,144			9,144
Adjustment to retained earnings | Accounting Standards Update 2016-16					(34,132)			(34,132)
Noncontrolling interest contributions (distributions)							(5,452)	(5,452)
Accrued distribution on redeemable noncontrolling interest in subsidiary					(11,098)			(11,098)
Other		$ 2	(3,872)					(3,870)
Other (in shares)		1,892
Balance at the end 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)					(702,885)		22,375	(680,510)
Dividends declared to common shareholders					(14,953)			(14,953)
Dividends declared to preferred shareholders					(17,245)			(17,245)
Other comprehensive income (loss), net of tax				17,537			55	17,592
Share-based compensation			24,659					24,659
Adjustment to retained earnings								0
Noncontrolling interest contributions (distributions)							(4,552)	(4,552)
Accrued distribution on redeemable noncontrolling interest in subsidiary					(20,534)			(20,534)
Other		$ 6	(4,624)					(4,618)
Other (in shares)	(137)	6,546
Balance at the end 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