SEGMENT DATA - Schedule of Operating Segment Results (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenue	$ 1,713,888	$ 1,537,416	$ 1,590,368	$ 1,329,322	$ 1,717,210	$ 1,566,582	$ 1,614,472	$ 1,361,798	$ 6,170,994	$ 6,260,062	$ 6,241,516
Direct operating expenses	654,188	621,895	614,377	571,262	627,186	591,740	613,186	566,664	2,461,722	2,398,776	2,471,113
Selling, general and administrative expenses	515,083	438,654	447,290	450,619	444,050	421,700	434,581	425,568	1,851,646	1,725,899	1,704,352
Corporate expenses	78,411	77,967	77,158	78,362	88,724	86,832	87,657	77,859	311,898	341,072	315,143
Depreciation and amortization	157,645	149,749	147,795	146,106	159,174	158,453	162,144	155,456	601,295	635,227	673,991
Impairment charges	2,568	7,631	0	0	0	8,000	0	0	10,199	8,000	21,631
Other operating income, net	10,919	(13,215)	6,916	31,084	133,788	(505)	(64,190)	284,463	35,704	353,556	94,001
Operating income (loss)	316,912	$ 228,305	$ 310,664	$ 114,057	531,864	$ 299,352	$ 252,714	$ 420,714	969,938	1,504,644	1,149,287
Segment assets	12,260,431				12,862,247				12,260,431	12,862,247	13,673,115
Capital expenditures									291,966	314,717	296,380
Share-based compensation expense									12,078	13,133	11,067
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									315,596	342,603	315,143
Depreciation and amortization									31,640	35,547	42,588
Impairment charges									10,199	8,000	21,631
Other operating income, net									35,704	353,556	94,001
Operating income (loss)									(321,731)	(32,594)	(285,361)
Segment assets	355,528				714,445				355,528	714,445	976,417
Capital expenditures									12,047	13,847	15,808
Share-based compensation expense									12,078	13,133	11,067
Eliminations
Segment Reporting Information [Line Items]
Revenue									(6,918)	(3,455)	(2,744)
Direct operating expenses									(166)	0	0
Selling, general and administrative expenses									(3,054)	(1,924)	(2,744)
Corporate expenses									(3,698)	(1,531)	0
Depreciation and amortization									0	0	0
Impairment charges									0	0	0
Other operating income, net									0	0	0
Operating income (loss)									0	0	0
Segment assets	(222)				(216)				(222)	(216)	(196,292)
Capital expenditures									0	0	0
Share-based compensation expense									0	0	0
Intersegment revenues
Segment Reporting Information [Line Items]
Revenue									6,918	3,455	2,744
Corporate And Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue									0	0	0
iHM | Operating Segments
Segment Reporting Information [Line Items]
Revenue									3,442,963	3,403,040	3,284,320
Direct operating expenses									1,059,123	975,463	972,937
Selling, general and administrative expenses									1,245,741	1,102,998	1,065,066
Corporate expenses									0	0	0
Depreciation and amortization									233,757	243,964	240,207
Impairment charges									0	0	0
Other operating income, net									0	0	0
Operating income (loss)									904,342	1,080,615	1,006,110
Segment assets	7,318,941				7,392,872				7,318,941	7,392,872	7,522,998
Capital expenditures									58,057	73,221	63,814
Share-based compensation expense									0	0	0
iHM | Intersegment revenues
Segment Reporting Information [Line Items]
Revenue									0	0	0
Americas Outdoor Advertising | Operating Segments
Segment Reporting Information [Line Items]
Revenue									1,256,326	1,278,413	1,349,021
Direct operating expenses									574,113	570,310	597,382
Selling, general and administrative expenses									219,467	225,415	233,254
Corporate expenses									0	0	0
Depreciation and amortization									189,707	185,654	204,514
Impairment charges									0	0	0
Other operating income, net									0	0	0
Operating income (loss)									273,039	297,034	313,871
Segment assets	2,969,326				3,175,355				2,969,326	3,175,355	3,567,764
Capital expenditures									74,580	81,401	82,165
Share-based compensation expense									0	0	0
Americas Outdoor Advertising | Intersegment revenues
Segment Reporting Information [Line Items]
Revenue									6,918	3,455	2,744
International Outdoor Advertising | Operating Segments
Segment Reporting Information [Line Items]
Revenue									1,334,939	1,410,471	1,457,183
Direct operating expenses									828,652	851,748	897,520
Selling, general and administrative expenses									289,170	289,787	298,250
Corporate expenses									0	0	0
Depreciation and amortization									131,224	152,758	166,060
Impairment charges									0	0	0
Other operating income, net									0	0	0
Operating income (loss)									85,893	116,178	95,353
Segment assets	1,449,365				1,342,356				1,449,365	1,342,356	1,573,161
Capital expenditures									146,392	143,788	132,554
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									143,684	171,593	153,736
Direct operating expenses									0	1,255	3,274
Selling, general and administrative expenses									100,322	109,623	110,526
Corporate expenses									0	0	0
Depreciation and amortization									14,967	17,304	20,622
Impairment charges									0	0	0
Other operating income, net									0	0	0
Operating income (loss)									28,395	43,411	19,314
Segment assets	$ 167,493				$ 237,435				167,493	237,435	229,067
Capital expenditures									890	2,460	2,039
Share-based compensation expense									$ 0	$ 0	$ 0