Quarterly Financial Data (Unaudited) (Schedule Of Quarterly Financial Data) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Data [Abstract]
TOTAL REVENUES, NET	$ 764,800	$ 729,426	$ 699,727	$ 720,411	$ 786,389	$ 745,466	$ 714,696	$ 700,527	$ 2,914,364	$ 2,947,078	$ 3,468,858
Gross profit	364,744	340,261	311,519	328,502	353,175	332,501	332,791	296,929
Loss from continuing operations	(208,489)	(41,431)	(98,052)	(12,612)	(265,479)	(146,071)	(52,479)	(497,738)	(360,584)	(961,767)	(1,232,711)
Discontinued operations, net of tax	(10,154)	(37,984)	(7,953)	(5,961)	(26,429)	(27,134)	(8,388)	(7,751)	(62,052)	(69,702)	(802,722)
Net loss	$ (218,643)	$ (79,415)	$ (106,005)	$ (18,573)	$ (291,908)	$ (173,205)	$ (60,867)	$ (505,489)	$ (422,636)	$ (1,031,469)	$ (2,035,433)
Continuing operations, basic (in dollars per share)	$ (0.92)	$ (0.18)	$ (0.43)	$ (0.06)	$ (1.18)	$ (0.65)	$ (0.23)	$ (2.23)	$ (1.60)	$ (4.29)	$ (5.52)
Discontinued operations, basic (in dollars per share)	(0.04)	(0.17)	(0.04)	(0.02)	(0.12)	(0.12)	(0.04)	(0.03)	(0.27)	(0.32)	(3.60)
Basic (in dollars per share)	(0.96)	(0.35)	(0.47)	(0.08)	(1.30)	(0.77)	(0.27)	(2.26)	(1.87)	(4.61)	(9.12)
Continuing operations, diluted (in dollars per share)	(0.92)	(0.18)	(0.43)	(0.06)	(1.18)	(0.65)	(0.23)	(2.23)	(1.60)	(4.29)	(5.52)
Discontinued operations, diluted (in dollars per share)	(0.04)	(0.17)	(0.04)	(0.02)	(0.12)	(0.12)	(0.04)	(0.03)	(0.27)	(0.32)	(3.60)
Diluted (in dollars per share)	$ (0.96)	$ (0.35)	$ (0.47)	$ (0.08)	$ (1.30)	$ (0.77)	$ (0.27)	$ (2.26)	$ (1.87)	$ (4.61)	$ (9.12)
Weighted average shares—Basic (in shares)	226,787	226,598	226,221	224,594	224,353	224,132	223,834	223,521	226,050	223,960	223,198
Weighted average shares—Diluted (in shares)	226,787	226,598	226,221	224,594	224,353	224,132	223,834	223,521	226,050	223,960	223,198
Acquisition-related and integration items, net	$ (19,100)	$ 16,000	$ (5,500)	$ (37,500)	$ 8,600	$ 1,300	$ 5,200	$ 6,800	$ (46,098)	$ 21,914	$ 58,086
Asset impairment charges	267,400	4,800	88,400	165,400	303,500	142,200	22,800	448,400	526,082	916,939	1,154,376
Restructuring charges	19,400	11,000	2,100	2,000	4,200	4,000	29,200	49,000
Litigation-related and other contingencies, net	15,300	(14,400)	10,300		(1,600)	(1,800)	19,600	(2,500)	(11,211)	(13,809)	(185,990)
Net gain on sale of business and other assets	$ (3,300)	$ (1,900)	$ (2,500)	$ 1,300	$ (15,300)	$ (2,900)	$ (24,600)	$ (2,400)	$ 6,367	$ 45,155	$ 13,809