CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Assets
Cash and cash equivalents	$ 988	$ 1,154
Accounts receivable, net of allowance of $2 at June 30, 2021 and December 31, 2020	539	583
Materials and supplies, net of allowance of $145 and $143 at June 30, 2021 and December 31, 2020, respectively	433	434
Restricted cash and cash equivalents	502	406
Other current assets	156	163
Total current assets	2,618	2,740
Property and equipment	23,054	23,040
Less accumulated depreciation	(5,718)	(5,373)
Property and equipment, net	17,336	17,667
Contract intangible assets	280	393
Deferred income taxes, net	8	9
Other assets	956	995
Total assets	21,198	21,804
Liabilities and equity
Accounts payable	198	194
Accrued income taxes	8	28
Debt due within one year	536	505
Other current liabilities	577	659
Total current liabilities	1,319	1,386
Long-term debt	6,991	7,302
Deferred income taxes, net	325	315
Other long-term liabilities	1,251	1,366
Total long-term liabilities	8,567	8,983
Commitments and contingencies
Shares, CHF 0.10 par value, 891,379,015 authorized, 142,363,647 conditionally authorized, 685,676,165 issued and 634,629,502 outstanding at June 30, 2021, and 824,650,660 authorized, 142,363,647 conditionally authorized, 639,676,165 issued and 615,140,276 outstanding at December 31, 2020	62	60
Additional paid-in capital	13,578	13,501
Accumulated deficit	(2,068)	(1,866)
Accumulated other comprehensive loss	(264)	(263)
Total controlling interest shareholders' equity	11,308	11,432
Noncontrolling interest	4	3
Total equity	11,312	11,435
Total liabilities and equity	$ 21,198	$ 21,804