SEGMENT DATA - Schedule of Operating Segment Results (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenue	$ 1,772,525	$ 1,582,765	$ 1,600,842	$ 1,369,648	$ 1,713,161	$ 1,536,757	$ 1,589,637	$ 1,328,876	$ 6,325,780	$ 6,168,431	$ 6,251,000
Direct operating expenses	663,688	630,264	636,641	602,355	656,219	623,741	616,221	572,543	2,532,948	2,468,724	2,395,037
Selling, general and administrative expenses	514,269	457,757	451,490	472,987	505,131	438,796	447,509	450,786	1,896,503	1,842,222	1,726,118
Corporate expenses	94,665	84,193	79,626	78,734	78,411	77,967	77,158	78,362	337,218	311,898	341,072
Depreciation and amortization	111,125	120,700	147,644	151,434	157,645	149,749	147,795	146,106	530,903	601,295	635,227
Impairment charges	0	40,922	0	0	2,568	7,631	0	0	40,922	10,199	8,000
Other operating income (expense), net	(1,556)	(1,637)	(289)	(3,286)	10,919	(13,215)	6,916	31,084	(6,768)	35,704	353,556
Operating income (loss)	387,222	$ 247,292	$ 285,152	$ 60,852	324,106	$ 225,658	$ 307,870	$ 112,163	980,518	969,797	1,499,102
Segment assets	12,269,515				12,260,431				12,269,515	12,260,431	12,851,789
Capital expenditures									296,324	291,966	314,717
Share-based compensation expense									10,583	12,078	13,133
Corporate and other reconciling items
Segment Reporting Information [Line Items]
Revenue									0	0	0
Direct operating expenses									0	0	0
Selling, general and administrative expenses									0	0	0
Corporate expenses									341,094	315,596	342,603
Depreciation and amortization									24,621	31,640	35,547
Impairment charges									40,922	10,199	8,000
Other operating income (expense), net									(6,768)	35,704	353,556
Operating income (loss)									(413,405)	(321,731)	(32,594)
Segment assets	393,993				355,528				393,993	355,528	714,445
Capital expenditures									11,138	12,047	13,847
Share-based compensation expense									10,583	12,078	13,133
Eliminations
Segment Reporting Information [Line Items]
Revenue									(7,315)	(6,918)	(3,455)
Direct operating expenses									(93)	(166)	0
Selling, general and administrative expenses									(3,346)	(3,054)	(1,924)
Corporate expenses									(3,876)	(3,698)	(1,531)
Depreciation and amortization									0	0	0
Impairment charges									0	0	0
Other operating income (expense), net									0	0	0
Operating income (loss)									0	0	0
Segment assets	(206)				(222)				(206)	(222)	(216)
Capital expenditures									0	0	0
Share-based compensation expense									0	0	0
Intersegment revenues
Segment Reporting Information [Line Items]
Revenue									7,315	6,918	3,455
iHM | Operating Segments
Segment Reporting Information [Line Items]
Revenue									3,436,955	3,442,963	3,403,040
Direct operating expenses									1,062,373	1,059,123	975,463
Selling, general and administrative expenses									1,271,152	1,245,741	1,102,998
Corporate expenses									0	0	0
Depreciation and amortization									177,775	233,757	243,964
Impairment charges									0	0	0
Other operating income (expense), net									0	0	0
Operating income (loss)									925,655	904,342	1,080,615
Segment assets	7,356,222				7,318,941				7,356,222	7,318,941	7,392,872
Capital expenditures									75,377	58,057	73,221
Share-based compensation expense									0	0	0
iHM | Intersegment revenues
Segment Reporting Information [Line Items]
Revenue									160	0	0
Americas Outdoor Advertising | Operating Segments
Segment Reporting Information [Line Items]
Revenue									1,189,348	1,161,059	1,187,180
Direct operating expenses									524,659	527,536	528,769
Selling, general and administrative expenses									199,688	197,390	203,427
Corporate expenses									0	0	0
Depreciation and amortization									166,806	179,119	175,438
Impairment charges									0	0	0
Other operating income (expense), net									0	0	0
Operating income (loss)									298,195	257,014	279,546
Segment assets	2,782,662				2,850,303				2,782,662	2,850,303	3,046,369
Capital expenditures									76,867	70,936	78,289
Share-based compensation expense									0	0	0
Americas Outdoor Advertising | Intersegment revenues
Segment Reporting Information [Line Items]
Revenue									7,155	6,918	3,455
International Outdoor Advertising | Operating Segments
Segment Reporting Information [Line Items]
Revenue									1,532,357	1,427,643	1,492,642
Direct operating expenses									946,009	882,231	889,550
Selling, general and administrative expenses									323,230	301,823	311,994
Corporate expenses									0	0	0
Depreciation and amortization									148,199	141,812	162,974
Impairment charges									0	0	0
Other operating income (expense), net									0	0	0
Operating income (loss)									114,919	101,777	128,124
Segment assets	1,568,346				1,568,388				1,568,346	1,568,388	1,460,884
Capital expenditures									129,962	150,036	146,900
Share-based compensation expense									0	0	0
International Outdoor Advertising | Intersegment revenues
Segment Reporting Information [Line Items]
Revenue									0	0	0
Other | Operating Segments
Segment Reporting Information [Line Items]
Revenue									174,435	143,684	171,593
Direct operating expenses									0	0	1,255
Selling, general and administrative expenses									105,779	100,322	109,623
Corporate expenses									0	0	0
Depreciation and amortization									13,502	14,967	17,304
Impairment charges									0	0	0
Other operating income (expense), net									0	0	0
Operating income (loss)									55,154	28,395	43,411
Segment assets	$ 168,498				$ 167,493				168,498	167,493	237,435
Capital expenditures									2,980	890	2,460
Share-based compensation expense									0	0	0
Other | Intersegment revenues
Segment Reporting Information [Line Items]
Revenue									$ 0	$ 0	$ 0