Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Operating activities
Net income		$ 908	$ 671
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization		1,600	1,575
Stock-based compensation expense		110	97
Deferred income tax expense		288	206
Bad debt expense		73	54
Losses from sales of receivables		35	52
Deferred rent expense		0	4
Losses on redemption of debt		0	32
Changes in operating assets and liabilities
Accounts receivable		(1,143)	(873)
Equipment installment plan receivables		(250)	(222)
Inventories		(265)	33
Operating lease right-of-use assets		435	0
Other current and long-term assets		(87)	132
Accounts payable and accrued liabilities		13	(1,028)
Short and long-term operating lease liabilities		(522)	0
Other current and long-term liabilities		121	45
Other, net		76	(8)
Net cash provided by operating activities		1,392	770
Investing activities
Purchases of property and equipment, including capitalized interest of $118 and $43		(1,931)	(1,366)
Purchases of spectrum licenses and other intangible assets, including deposits		(185)	(51)
Proceeds related to beneficial interests in securitization transactions		1,157	1,295
Acquisition of companies, net of cash acquired		0	(333)
Other, net		(7)	(7)
Net cash used in investing activities		(966)	(462)
Financing activities
Proceeds from issuance of long-term debt		0	2,494
Proceeds from borrowing on revolving credit facility		885	2,170
Repayments of revolving credit facility		(885)	(1,725)
Repayments of financing lease obligations		(86)	(172)
Repayments of long-term debt		0	(999)
Repurchases of common stock		0	(666)
Tax withholdings on share-based awards		(100)	(74)
Cash payments for debt prepayment or debt extinguishment costs		0	(31)
Other, net		(4)	3
Net cash (used in) provided by financing activities		(190)	1,000
Change in cash and cash equivalents		236	1,308
Cash and cash equivalents
Beginning of period		1,203	1,219
End of period		1,439	2,527
Supplemental disclosure of cash flow information
Interest payments, net of amounts capitalized		340	378
Operating lease payments (1)	[1]	688	0
Income tax payments		32	1
Noncash investing and financing activities
Noncash beneficial interest obtained in exchange for securitized receivables		1,512	1,128
Changes in accounts payable for purchases of property and equipment		(333)	(364)
Leased devices transferred from inventory to property and equipment		147	304
Returned leased devices transferred from property and equipment to inventory		(57)	(82)
Short-term debt assumed for financing of property and equipment		250	237
Operating lease right-of-use assets obtained in exchange for lease obligations		694	0
Financing lease right-of-use assets obtained in exchange for lease obligations		$ 180	$ 142

[1] On January 1, 2019, we adopted ASU 2016-02, “Leases (Topic 842),” which requires certain supplemental cash flow disclosures. Where these disclosures or a comparable figure were not required under the former lease standard, we have not retrospectively presented historical amounts. See Note 1 – Summary of Significant Accounting Policies for additional details.