Earnings (Losses) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jan. 31, 2017
Net income (loss) (numerator):
Income (loss) from continuing operations, net of tax	$ (115,476)	$ (186,565)	$ (263,104)	$ (583,209)
Less: net (income) loss attributable to noncontrolling interest	(1,971)	2,899	(2,888)	2,175
Less: (earnings) losses allocated to unvested shareholders	3,306	3,786	7,117	11,985
Adjusted income (loss) from continuing operations, net of tax - basic	(114,141)	(179,880)	(258,875)	(569,049)
Income (loss) from discontinued operations, net of tax	$ (15,504)	$ (984)	$ (15,943)	$ (1,910)
Weighted-average number of shares outstanding - basic	278,916	276,550	278,348	276,201
Earnings (losses) Per Share - Basic
Basic from continuing operations (in dollars per share)	$ (0.41)	$ (0.65)	$ (0.93)	$ (2.06)
Basic from discontinued operations (in dollars per share)	(0.05)		(0.06)	(0.01)
Total Basic (in dollars per share)	$ (0.46)	$ (0.65)	$ (0.99)	$ (2.07)
DILUTED EPS:
Adjusted income (loss) from continuing operations, net of tax - basic	$ (114,141)	$ (179,880)	$ (258,875)	$ (569,049)
Adjusted income (loss) from continuing operations, net of tax - diluted	(114,141)	(179,880)	(258,875)	(569,049)
Income (loss) from discontinued operations, net of tax	$ (15,504)	$ (984)	$ (15,943)	$ (1,910)
Weighted-average number of shares outstanding - basic	278,916	276,550	278,348	276,201
Weighted-average number of shares outstanding - diluted	278,916	276,550	278,348	276,201
Earnings (losses) per share:
Diluted from continuing operations (in dollars per share)	$ (0.41)	$ (0.65)	$ (0.93)	$ (2.06)
Diluted from discontinued operations (in dollars per share)	(0.05)		(0.06)	(0.01)
Total Diluted (in dollars per share)	$ (0.46)	$ (0.65)	$ (0.99)	$ (2.07)
0.75% senior exchangeable notes due January 2024
Earnings (losses) per share:
Aggregate amount of senior notes	$ 575,000		$ 575,000		$ 575,000
Interest rate on senior notes due (as a percent)	0.75%		0.75%
0.75% senior exchangeable notes due January 2024 | Minimum
Earnings (losses) per share:
Share issued price (in dollars per share)	$ 25.16		$ 25.16