Guarantor and Non-Guarantor Subsidiaries Financial Information - Consolidating Balance Sheet (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015
Current assets:
Cash and equivalents	$ 476	$ 359	$ 316	$ 246
Accounts receivable, net	361	329
Inventories	36	41
Royalty advances expected to be recouped within one year	125	128
Prepaid and other current assets	57	51
Total current assets	1,055	908
Royalty advances expected to be recouped after one year	194	196
Property, plant and equipment, net	197	203
Goodwill	1,614	1,627
Intangible assets subject to amortization, net	2,056	2,201
Intangible assets not subject to amortization	116	116
Other assets	72	84
Total assets	5,304	5,335
Current liabilities:
Accounts payable	200	204
Accrued royalties	1,151	1,104
Accrued liabilities	260	297
Accrued interest	45	38
Deferred revenue	175	178
Other current liabilities	24	21
Total current liabilities	1,855	1,842
Long-term debt	2,767	2,778
Deferred tax liabilities, net	254	269
Other noncurrent liabilities	241	236
Total liabilities	5,117	5,125
Total Warner Music Group Corp. equity	170	195
Noncontrolling interest	17	15
Total equity	187	210
Total liabilities and equity	5,304	5,335
Reportable Legal Entities | WMG Acquisition Corp.
Current assets:
Prepaid and other current assets		1
Total current assets		1
Due (to) from parent companies	721	750
Investments in and advances to consolidated subsidiaries	2,261	2,260
Other assets	3	3
Total assets	2,985	3,014
Current liabilities:
Accrued interest	45	38
Total current liabilities	45	38
Long-term debt	2,767	2,778
Other noncurrent liabilities	3	3
Total liabilities	2,815	2,819
Total Warner Music Group Corp. equity	170	195
Total equity	170	195
Total liabilities and equity	2,985	3,014
Reportable Legal Entities | Guarantor Subsidiaries
Current assets:
Cash and equivalents	230	180	83	73
Accounts receivable, net	175	177
Inventories	12	16
Royalty advances expected to be recouped within one year	80	79
Prepaid and other current assets	15	13
Total current assets	512	465
Due (to) from parent companies	(286)	(312)
Investments in and advances to consolidated subsidiaries	1,592	1,458
Royalty advances expected to be recouped after one year	123	120
Property, plant and equipment, net	132	138
Goodwill	1,372	1,372
Intangible assets subject to amortization, net	1,114	1,165
Intangible assets not subject to amortization	71	71
Other assets	50	62
Total assets	4,680	4,539
Current liabilities:
Accounts payable	117	124
Accrued royalties	649	606
Accrued liabilities	91	112
Deferred revenue	112	143
Other current liabilities	3	3
Total current liabilities	972	988
Deferred tax liabilities, net	115	109
Other noncurrent liabilities	132	126
Total liabilities	1,219	1,223
Total Warner Music Group Corp. equity	3,459	3,314
Noncontrolling interest	2	2
Total equity	3,461	3,316
Total liabilities and equity	4,680	4,539
Reportable Legal Entities | Non-Guarantor Subsidiaries
Current assets:
Cash and equivalents	246	179	217	173
Accounts receivable, net	186	152
Inventories	24	25
Royalty advances expected to be recouped within one year	45	49
Prepaid and other current assets	42	37
Total current assets	543	442
Due (to) from parent companies	(435)	(438)
Royalty advances expected to be recouped after one year	71	76
Property, plant and equipment, net	65	65
Goodwill	242	255
Intangible assets subject to amortization, net	942	1,036
Intangible assets not subject to amortization	45	45
Other assets	19	19
Total assets	1,492	1,500
Current liabilities:
Accounts payable	83	80
Accrued royalties	502	498
Accrued liabilities	169	185
Deferred revenue	63	35
Other current liabilities	21	18
Total current liabilities	838	816
Deferred tax liabilities, net	139	160
Other noncurrent liabilities	106	107
Total liabilities	1,083	1,083
Total Warner Music Group Corp. equity	394	404
Noncontrolling interest	15	13
Total equity	409	417
Total liabilities and equity	1,492	1,500
Reportable Legal Entities | WMG Acquisition Corp. Consolidated
Current assets:
Cash and equivalents	476	359	300	$ 246
Accounts receivable, net	361	329
Inventories	36	41
Royalty advances expected to be recouped within one year	125	128
Prepaid and other current assets	57	51
Total current assets	1,055	908
Royalty advances expected to be recouped after one year	194	196
Property, plant and equipment, net	197	203
Goodwill	1,614	1,627
Intangible assets subject to amortization, net	2,056	2,201
Intangible assets not subject to amortization	116	116
Other assets	72	84
Total assets	5,304	5,335
Current liabilities:
Accounts payable	200	204
Accrued royalties	1,151	1,104
Accrued liabilities	260	297
Accrued interest	45	38
Deferred revenue	175	178
Other current liabilities	24	21
Total current liabilities	1,855	1,842
Long-term debt	2,767	2,778
Deferred tax liabilities, net	254	269
Other noncurrent liabilities	241	236
Total liabilities	5,117	5,125
Total Warner Music Group Corp. equity	170	195
Noncontrolling interest	17	15
Total equity	187	210
Total liabilities and equity	5,304	5,335
Reportable Legal Entities | WMG Holdings Corp.
Current assets:
Cash and equivalents			$ 16
Investments in and advances to consolidated subsidiaries	224	195
Total assets	224	195
Current liabilities:
Total Warner Music Group Corp. equity	224	195
Total equity	224	195
Total liabilities and equity	224	195
Reportable Legal Entities | Warner Music Group Corp.
Current assets:
Investments in and advances to consolidated subsidiaries	224	195
Total assets	224	195
Current liabilities:
Total Warner Music Group Corp. equity	224	195
Total equity	224	195
Total liabilities and equity	224	195
Eliminations
Current assets:
Investments in and advances to consolidated subsidiaries	(448)	(390)
Total assets	(448)	(390)
Current liabilities:
Total Warner Music Group Corp. equity	(448)	(390)
Total equity	(448)	(390)
Total liabilities and equity	(448)	(390)
Eliminations | WMG Acquisition Corp.
Current assets:
Investments in and advances to consolidated subsidiaries	(3,853)	(3,718)
Total assets	(3,853)	(3,718)
Current liabilities:
Total Warner Music Group Corp. equity	(3,853)	(3,718)
Total equity	(3,853)	(3,718)
Total liabilities and equity	$ (3,853)	$ (3,718)