Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net income	$ 978	$ 110	$ 1,911	$ 1,061
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	4,077	4,064	8,366	5,782
Stock-based compensation expense	134	259	272	397
Deferred income tax expense	226	98	437	408
Bad debt expense	72	233	154	346
(Gains) losses from sales of receivables	(12)	30	(30)	55
Losses on redemption of debt	28	163	129	163
Impairment expense	0	418	0	418
Changes in operating assets and liabilities
Accounts receivable	(1,839)	(498)	(1,743)	(1,246)
Equipment installment plan receivables	(568)	127	(1,295)	196
Inventories	584	(553)	863	(1,064)
Operating lease right-of-use assets	1,272	937	2,396	1,464
Other current and long-term assets	(154)	(104)	(100)	(98)
Accounts payable and accrued liabilities	28	(1,261)	(1,356)	(1,666)
Short and long-term operating lease liabilities	(996)	(1,077)	(2,365)	(1,802)
Other current and long-term liabilities	(47)	(2,190)	(264)	(2,111)
Other, net	(4)	21	65	91
Net cash provided by operating activities	3,779	777	7,440	2,394
Investing activities
Purchases of property and equipment, including capitalized interest of $57, $119, $141, and $231	(3,270)	(2,257)	(6,453)	(4,010)
Purchases of spectrum licenses and other intangible assets, including deposits	(8)	(745)	(8,930)	(844)
Proceeds from sales of tower sites	31	0	31	0
Proceeds related to beneficial interests in securitization transactions	1,137	602	2,028	1,470
Net cash related to derivative contracts under collateral exchange arrangements	0	1,212	0	632
Acquisition of companies, net of cash and restricted cash acquired	(1)	(5,000)	(30)	(5,000)
Other, net	28	(168)	32	(184)
Net cash used in investing activities	(2,083)	(6,356)	(13,322)	(7,936)
Financing activities
Proceeds from issuance of long-term debt	3,006	26,694	9,769	26,694
Payments of consent fees related to long-term debt	0	(109)	0	(109)
Repayments of financing lease obligations	(269)	(236)	(556)	(518)
Repayments of short-term debt for purchases of inventory, property and equipment and other financial liabilities	(36)	(151)	(91)	(176)
Repayments of long-term debt	(3,150)	(10,529)	(5,369)	(10,529)
Issuance of common stock	0	17,290	0	17,290
Repurchases of common stock	0	(16,990)	0	(16,990)
Proceeds from issuance of short-term debt	0	18,743	0	18,743
Repayments of short-term debt	0	(18,929)	0	(18,929)
Tax withholdings on share-based awards	(76)	(138)	(294)	(279)
Cash payments for debt prepayment or debt extinguishment costs	(6)	(24)	(71)	(24)
Other, net	(46)	7	(91)	2
Net cash (used in) provided by financing activities	(577)	15,628	3,297	15,175
Change in cash and cash equivalents, including restricted cash	1,119	10,049	(2,585)	9,633
Cash and cash equivalents, including restricted cash
Beginning of period	6,759	1,112	10,463	1,528
End of period	$ 7,878	$ 11,161	$ 7,878	$ 11,161