Supplemental Condensed Consolidated Financial Information (Condensed Consolidated Balance Sheet) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	$ 120,122	$ 102,891
Restricted cash	9,004	8,999
Accounts receivable, less allowance for doubtful accounts	212,010	235,247
Trade receivable	5,612	4,224
Prepaid expenses and other current assets	51,720	42,259
Total current assets	398,468	393,620
Property and equipment, net	193,322	191,604
Broadcast licenses	1,203,809	1,203,809
Other intangible assets, net	78,289	82,994
Goodwill	135,214	135,214
Investment in consolidated subsidiaries	0	0
Intercompany receivables	0	0
Other assets	20,772	20,078
Total assets	2,029,874	2,027,319
Accounts payable and accrued expenses	86,661	36,157
Total current liabilities	86,661	36,157
Other liabilities	179	54
Intercompany payables	0	0
Accumulated losses in consolidated subsidiaries	0	0
Total liabilities not subject to compromise	86,840	36,211
Liabilities subject to compromise	2,643,984	2,687,223
Total liabilities	2,730,824	2,723,434
Treasury stock, at cost	(229,310)	(229,310)
Additional paid-in-capital	1,626,594	1,626,428
Accumulated deficit	(2,098,555)	(2,093,554)
Total stockholders’ deficit	(700,950)	(696,115)
Total liabilities and stockholders’ deficit	2,029,874	2,027,319
Eliminations
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Accounts receivable, less allowance for doubtful accounts	0	0
Trade receivable	0	0
Prepaid expenses and other current assets	0	0
Total current assets	0	0
Property and equipment, net	0	0
Broadcast licenses	0	0
Other intangible assets, net	0	0
Goodwill	0	0
Investment in consolidated subsidiaries	(4,290,248)	(4,308,272)
Intercompany receivables	(1,914,854)	(1,912,503)
Other assets	0	0
Total assets	(6,205,102)	(6,220,775)
Accounts payable and accrued expenses	0	0
Total current liabilities	0	0
Other liabilities	0	0
Intercompany payables	(1,914,854)	(1,912,503)
Accumulated losses in consolidated subsidiaries	(586,802)	(584,151)
Total liabilities not subject to compromise	(2,501,656)	(2,496,654)
Liabilities subject to compromise	0	0
Total liabilities	(2,501,656)	(2,496,654)
Treasury stock, at cost	0	0
Additional paid-in-capital	(6,658,139)	(6,699,116)
Accumulated deficit	2,954,693	2,974,995
Total stockholders’ deficit	(3,703,446)	(3,724,121)
Total liabilities and stockholders’ deficit	(6,205,102)	(6,220,775)
Cumulus Media Inc. (Parent Guarantor)
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Accounts receivable, less allowance for doubtful accounts	0	0
Trade receivable	0	0
Prepaid expenses and other current assets	0	0
Total current assets	0	0
Property and equipment, net	0	0
Broadcast licenses	0	0
Other intangible assets, net	0	0
Goodwill	0	0
Investment in consolidated subsidiaries	0	0
Intercompany receivables	0	0
Other assets	0	0
Total assets	0	0
Accounts payable and accrued expenses	0	0
Total current liabilities	0	0
Other liabilities	0	0
Intercompany payables	114,148	111,964
Accumulated losses in consolidated subsidiaries	586,802	584,151
Total liabilities not subject to compromise	700,950	696,115
Liabilities subject to compromise	0	0
Total liabilities	700,950	696,115
Treasury stock, at cost	(229,310)	(229,310)
Additional paid-in-capital	1,626,594	1,626,428
Accumulated deficit	(2,098,555)	(2,093,554)
Total stockholders’ deficit	(700,950)	(696,115)
Total liabilities and stockholders’ deficit	0	0
Cumulus Media Holdings Inc. (Subsidiary Issuer)
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	120,122	102,891
Restricted cash	9,004	8,999
Accounts receivable, less allowance for doubtful accounts	0	0
Trade receivable	0	0
Prepaid expenses and other current assets	23,199	25,393
Total current assets	152,325	137,283
Property and equipment, net	20,550	14,404
Broadcast licenses	0	0
Other intangible assets, net	0	0
Goodwill	0	0
Investment in consolidated subsidiaries	3,305,567	3,323,713
Intercompany receivables	114,148	111,964
Other assets	6,455	6,507
Total assets	3,599,045	3,593,871
Accounts payable and accrued expenses	29,819	8,653
Total current liabilities	29,819	8,653
Other liabilities	159	53
Intercompany payables	1,800,706	1,800,539
Accumulated losses in consolidated subsidiaries	0	0
Total liabilities not subject to compromise	1,830,684	1,809,245
Liabilities subject to compromise	2,355,164	2,368,777
Total liabilities	4,185,848	4,178,022
Treasury stock, at cost	0	0
Additional paid-in-capital	280,606	279,811
Accumulated deficit	(867,408)	(863,962)
Total stockholders’ deficit	(586,802)	(584,151)
Total liabilities and stockholders’ deficit	3,599,045	3,593,871
Subsidiary Guarantors
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Accounts receivable, less allowance for doubtful accounts	212,010	235,247
Trade receivable	5,612	4,224
Prepaid expenses and other current assets	28,521	16,866
Total current assets	246,143	256,337
Property and equipment, net	172,772	177,200
Broadcast licenses	0	0
Other intangible assets, net	78,289	82,994
Goodwill	135,214	135,214
Investment in consolidated subsidiaries	984,681	984,559
Intercompany receivables	1,800,706	1,800,539
Other assets	14,317	13,571
Total assets	3,432,122	3,450,414
Accounts payable and accrued expenses	56,842	27,504
Total current liabilities	56,842	27,504
Other liabilities	20	1
Intercompany payables	0	0
Accumulated losses in consolidated subsidiaries	0	0
Total liabilities not subject to compromise	56,862	27,505
Liabilities subject to compromise	69,692	99,196
Total liabilities	126,554	126,701
Treasury stock, at cost	0	0
Additional paid-in-capital	4,173,435	4,215,794
Accumulated deficit	(867,868)	(892,081)
Total stockholders’ deficit	3,305,567	3,323,713
Total liabilities and stockholders’ deficit	3,432,122	3,450,414
Subsidiary Non-guarantors
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Accounts receivable, less allowance for doubtful accounts	0	0
Trade receivable	0	0
Prepaid expenses and other current assets	0	0
Total current assets	0	0
Property and equipment, net	0	0
Broadcast licenses	1,203,809	1,203,809
Other intangible assets, net	0	0
Goodwill	0	0
Investment in consolidated subsidiaries	0	0
Intercompany receivables	0	0
Other assets	0	0
Total assets	1,203,809	1,203,809
Accounts payable and accrued expenses	0	0
Total current liabilities	0	0
Other liabilities	0	0
Intercompany payables	0	0
Accumulated losses in consolidated subsidiaries	0	0
Total liabilities not subject to compromise	0	0
Liabilities subject to compromise	219,128	219,250
Total liabilities	219,128	219,250
Treasury stock, at cost	0	0
Additional paid-in-capital	2,204,098	2,203,511
Accumulated deficit	(1,219,417)	(1,218,952)
Total stockholders’ deficit	984,681	984,559
Total liabilities and stockholders’ deficit	1,203,809	1,203,809
Class A common stock
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	320	320
Class A common stock | Eliminations
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	0	0
Class A common stock | Cumulus Media Inc. (Parent Guarantor)
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	320	320
Class A common stock | Cumulus Media Holdings Inc. (Subsidiary Issuer)
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	0	0
Class A common stock | Subsidiary Guarantors
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	0	0
Class A common stock | Subsidiary Non-guarantors
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	0	0
Class C common stock
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	1	1
Class C common stock | Eliminations
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	0	0
Class C common stock | Cumulus Media Inc. (Parent Guarantor)
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	1	1
Class C common stock | Cumulus Media Holdings Inc. (Subsidiary Issuer)
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	0	0
Class C common stock | Subsidiary Guarantors
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	0	0
Class C common stock | Subsidiary Non-guarantors
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock	$ 0	$ 0