CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In- Capital	Treasury Stock	Accumulated Deficit	Noncontrolling Interest
Balances at beginning of period at Dec. 31, 2017	$ 1,530,291	$ 1,913	$ 4,126,549	$ (56,440)	$ (2,541,294)	$ (437)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(659,883)				(659,797)	(86)
Compensation expense related to restricted stock grants			20,710
Issuance of common stock under Associate Stock Purchase Plan		1	1,146
Restricted stock, net		29	(29)
Shares withheld for employee taxes		(4)	(2,840)
Purchase of treasury stock				0
Noncontrolling interest contribution						0
Other, net			147		280
Balances at end of period at Sep. 30, 2018	889,848	$ 1,939	4,145,683	(56,440)	(3,200,811)	(523)
Balances at beginning of period (in shares) at Dec. 31, 2017		191,276,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under Associate Stock Purchase Plan (in shares)		153,000
Restricted stock, net (in shares)		2,910,000
Shares withheld for employee taxes (in shares)		(410,000)
Purchase of treasury stock (in shares)		0
Balances at end of period (in shares) at Sep. 30, 2018		193,929,000
Balances at beginning of period at Jun. 30, 2018	920,657	$ 1,938	4,139,353	(56,440)	(3,163,690)	(504)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(37,140)				(37,121)	(19)
Compensation expense related to restricted stock grants			6,035
Issuance of common stock under Associate Stock Purchase Plan		0	377
Restricted stock, net		1	(1)
Shares withheld for employee taxes		0	(129)
Purchase of treasury stock				0
Noncontrolling interest contribution						0
Other, net			48		0
Balances at end of period at Sep. 30, 2018	889,848	$ 1,939	4,145,683	(56,440)	(3,200,811)	(523)
Balances at beginning of period (in shares) at Jun. 30, 2018		193,798,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under Associate Stock Purchase Plan (in shares)		42,000
Restricted stock, net (in shares)		105,000
Shares withheld for employee taxes (in shares)		(16,000)
Purchase of treasury stock (in shares)		0
Balances at end of period (in shares) at Sep. 30, 2018		193,929,000
Balances at beginning of period at Dec. 31, 2018	1,018,413	$ 1,968	4,151,147	(64,940)	(3,069,272)	(490)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(177,169)				(176,523)	(646)
Compensation expense related to restricted stock grants			18,315
Issuance of common stock under Associate Stock Purchase Plan		2	878
Restricted stock, net		31	(31)
Shares withheld for employee taxes		(4)	(3,238)
Purchase of treasury stock				(14,157)
Noncontrolling interest contribution						6,566
Other, net			75		0
Balances at end of period at Sep. 30, 2019	$ 793,796	$ 1,997	4,167,146	(79,097)	(3,301,680)	5,430
Balances at beginning of period (in shares) at Dec. 31, 2018	192,356,051	192,356,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under Associate Stock Purchase Plan (in shares)		137,000
Restricted stock, net (in shares)		3,258,000
Shares withheld for employee taxes (in shares)		(467,000)
Purchase of treasury stock (in shares)		(2,211,000)
Balances at end of period (in shares) at Sep. 30, 2019	193,073,421	193,073,000
Balances at beginning of period at Jun. 30, 2019	$ 866,204	$ 1,998	4,161,045	(79,097)	(3,223,222)	5,480
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(78,508)				(78,458)	(50)
Compensation expense related to restricted stock grants			5,929
Issuance of common stock under Associate Stock Purchase Plan		0	281
Restricted stock, net		(1)	1
Shares withheld for employee taxes		0	(137)
Purchase of treasury stock				0
Noncontrolling interest contribution						0
Other, net			27		0
Balances at end of period at Sep. 30, 2019	$ 793,796	$ 1,997	$ 4,167,146	$ (79,097)	$ (3,301,680)	$ 5,430
Balances at beginning of period (in shares) at Jun. 30, 2019		193,111,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under Associate Stock Purchase Plan (in shares)		41,000
Restricted stock, net (in shares)		(62,000)
Shares withheld for employee taxes (in shares)		(17,000)
Purchase of treasury stock (in shares)		0
Balances at end of period (in shares) at Sep. 30, 2019	193,073,421	193,073,000