Fresh Start Accounting (Fresh Start - Balance Sheet) (Details) - USD ($) $ in Millions	May 01, 2021	Apr. 30, 2021	Jun. 30, 2020
LIABILITIES
Liabilities subject to compromise		$ 11,570
ASSETS
Cash and cash equivalents	$ (1,169)
Equity (Deficit):
Retained earnings (deficit)		10,028
Reorganization Adjustments [Member]
ASSETS
Cash and cash equivalents		(1,169)
Accounts receivable, net
Contract acquisition costs
Prepaid expenses
Income taxes and other current assets
Total current assets		(1,169)
Property, plant and equipment, net of accumulated depreciation and depletion
Other intangibles, net
Other assets		(8)
Total assets		(1,177)
LIABILITIES
Long-term debt due within one year		(5,767)
Accounts payable		(6)
Advanced billings
Accrued other taxes
Accrued interest		(1)
Other current liabilities		53
Total current liabilities		(5,721)
Deferred income taxes		70
Pension and other postretirement benefits
Other liabilities
Long-term debt		6,738
Total liabilities not subject to compromise		1,087
Liabilities subject to compromise		(11,570)
Total liabilities		(10,483)
Equity (Deficit):
Retained earnings (deficit)		10,028
Accumulated other comprehensive income (loss), net of tax
Treasury common stock		15
Total equity (deficit)		9,306
Total liabilities and equity (deficit)		(1,177)
Fresh Start Adjustments [Member]
ASSETS
Cash and cash equivalents
Accounts receivable, net
Contract acquisition costs		(91)
Prepaid expenses
Income taxes and other current assets		(3)
Total current assets		(94)
Property, plant and equipment, net of accumulated depreciation and depletion		(4,473)
Other intangibles, net		3,863
Other assets		(120)
Total assets		(824)
LIABILITIES
Long-term debt due within one year
Accounts payable
Advanced billings
Accrued other taxes
Accrued interest
Pension and other postretirement benefits
Other current liabilities		(36)
Total current liabilities		(36)
Deferred income taxes		(168)
Pension and other postretirement benefits		(437)
Other liabilities		(28)
Long-term debt		277
Total liabilities not subject to compromise		(392)
Liabilities subject to compromise
Total liabilities		(392)
Equity (Deficit):
Retained earnings (deficit)		(1,173)
Accumulated other comprehensive income (loss), net of tax		741
Treasury common stock
Total equity (deficit)		(432)
Total liabilities and equity (deficit)		(824)
Successor [Member]
Equity (Deficit):
Common stock
Additional paid-in capital
ASSETS
Cash and cash equivalents		890
Accounts receivable, net		516
Contract acquisition costs
Prepaid expenses		92
Income taxes and other current assets		42
Total current assets		1,540
Property, plant and equipment, net of accumulated depreciation and depletion		8,547	$ 8,547
Other intangibles, net		4,441
Other assets		398
Total assets		14,926
LIABILITIES
Long-term debt due within one year		15
Accounts payable		512
Advanced billings		208
Accrued other taxes		185
Accrued interest		80
Pension and other postretirement benefits		48
Other current liabilities		326
Total current liabilities		1,374
Deferred income taxes		291	291
Pension and other postretirement benefits		1,726
Other liabilities		412
Long-term debt		7,015
Total liabilities not subject to compromise		10,818
Liabilities subject to compromise
Total liabilities		10,818
Equity (Deficit):
Common stock		2
Additional paid-in capital		4,106
Retained earnings (deficit)
Accumulated other comprehensive income (loss), net of tax
Treasury common stock
Total equity (deficit)		4,108	$ 4,108
Total liabilities and equity (deficit)		14,926
Successor [Member] | Reorganization Adjustments [Member]
Equity (Deficit):
Common stock		2
Additional paid-in capital		4,106
Successor [Member] | Fresh Start Adjustments [Member]
Equity (Deficit):
Common stock
Additional paid-in capital
Predecessor [Member]
Current assets:
Cash and cash equivalents		2,059
Accounts receivable, net		516
Contract acquisition costs		91
Prepaid expenses		92
Income taxes and other current assets		45
Total current assets		2,803
Property, plant and equipment, net		13,020
Other intangibles, net		578
Other assets		526
Total assets		16,927
LIABILITIES
Long-term debt due within one year		5,782
Accounts payable		518
Advanced billings		208
Accrued other taxes		185
Accrued interest		81
Pension and other postretirement benefits		48
Other current liabilities		309
Total current liabilities		7,131
Deferred income taxes		389
Pension and other postretirement benefits		2,163
Other liabilities		440
Long-term debt
Total liabilities not subject to compromise		10,123
Liabilities subject to compromise		11,570
Total liabilities		21,693
Equity (Deficit):
Common stock		27
Additional paid-in capital		4,818
Retained earnings (deficit)		(8,855)
Accumulated other comprehensive income (loss), net of tax		(741)
Treasury common stock		(15)
Total equity (deficit)		(4,766)
Total liabilities and equity (deficit)		16,927
LIABILITIES
Long-term debt		277
Equity (Deficit):
Common stock
Additional paid-in capital
Predecessor [Member] | Reorganization Adjustments [Member]
Equity (Deficit):
Common stock		(27)
Additional paid-in capital		(4,818)
Predecessor [Member] | Fresh Start Adjustments [Member]
Equity (Deficit):
Common stock
Additional paid-in capital