Planned Divestiture of the Latin American and ILEC Businesses - Components of Held for Sale Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2021	Aug. 03, 2021	Sep. 30, 2020
Assets held for sale
Cash and cash equivalents	$ 39		$ 0
Defined Benefit Plan, Funded Plan
Liabilities held for sale
Pension liability	2,500
Defined Benefit Plan, Funded through Transfer of Plan Assets
Liabilities held for sale
Pension liability	$ 2,200
Funded percentage	89.00%
Disposal Group, Held-for-sale, Not Discontinued Operations
Assets held for sale
Cash and cash equivalents	$ 39
Accounts receivable, less allowance of $3, $21 and $24	313
Other current assets	121
Property, plant and equipment, net accumulated depreciation of $445, $10,976 and $11,421	4,931
Goodwill	2,859
Other intangible assets, net	287
Other non-current assets	112
Total assets held for sale	8,662
Liabilities held for sale
Accounts payable	155
Salaries and benefits	50
Income and other taxes	63
Interest	38
Current portion of deferred revenue	118
Other current liabilities	53
Long-term debt, net of discounts	1,367
Deferred income taxes, net	116
Pension and other post-retirement benefits	58
Other non-current liabilities	273
Total liabilities held for sale	2,291
Allowance for doubtful accounts	24
Accumulated depreciation	11,421
Long-term finance lease obligations	48
Disposal Group, Held-for-sale, Not Discontinued Operations | Senior notes | Embarq
Liabilities held for sale
Long-term debt, net of discounts	1,400
Unamortized discount	118
Disposal Group, Held-for-sale, Not Discontinued Operations | Latin American Business
Assets held for sale
Cash and cash equivalents	37
Accounts receivable, less allowance of $3, $21 and $24	83
Other current assets	75
Property, plant and equipment, net accumulated depreciation of $445, $10,976 and $11,421	1,545
Goodwill	244
Other intangible assets, net	129
Other non-current assets	71
Total assets held for sale	2,184
Liabilities held for sale
Accounts payable	76
Salaries and benefits	22
Income and other taxes	32
Interest	0
Current portion of deferred revenue	28
Other current liabilities	10
Long-term debt, net of discounts	0
Deferred income taxes, net	116
Pension and other post-retirement benefits	2
Other non-current liabilities	126
Total liabilities held for sale	412
Allowance for doubtful accounts	3
Accumulated depreciation	445
Disposal Group, Held-for-sale, Not Discontinued Operations | ILEC Business
Assets held for sale
Cash and cash equivalents	2
Accounts receivable, less allowance of $3, $21 and $24	230
Other current assets	46
Property, plant and equipment, net accumulated depreciation of $445, $10,976 and $11,421	3,386
Goodwill	2,615
Other intangible assets, net	158
Other non-current assets	41
Total assets held for sale	6,478
Liabilities held for sale
Accounts payable	79
Salaries and benefits	28
Income and other taxes	31
Interest	38
Current portion of deferred revenue	90
Other current liabilities	43
Long-term debt, net of discounts	1,367
Deferred income taxes, net	0
Pension and other post-retirement benefits	56
Other non-current liabilities	147
Total liabilities held for sale	1,879	$ 1,400
Allowance for doubtful accounts	21
Accumulated depreciation	10,976
Discontinued Operations, Held-for-sale
Assets held for sale
Total assets held for sale	$ 20