Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Income before Income Tax

Our sources of Income before income taxes were as follows:

	Year Ended December 31,
(in millions)	2019		2018		2017
U.S.	$	4,557	$	3,686	$	3,274
Puerto Rico	46		231		(113)
Income before income taxes	$	4,603	$	3,917	$	3,161

Schedule of Components of Income Tax Expense (Benefit)

Income tax (expense) benefit is summarized as follows:

	Year Ended December 31,
(in millions)	2019		2018		2017
Current tax benefit (expense)
Federal	$	24	$	39	$	—
State	(70)		(63)		(28)
Puerto Rico	2		(25)		(1)
Total current tax expense	(44)		(49)		(29)
Deferred tax benefit (expense)
Federal	(954)		(750)		1,182
State	(125)		(160)		173
Puerto Rico	(12)		(70)		49
Total deferred tax (expense) benefit	(1,091)		(980)		1,404
Total income tax (expense) benefit	$	(1,135)	$	(1,029)	$	1,375

Schedule of Effective Income Tax Rate Reconciliation

The reconciliation between the U.S. federal statutory income tax rate and our effective income tax rate is as follows:

	Year Ended December 31,
	2019		2018		2017
Federal statutory income tax rate	21.0	%	21.0	%	35.0	%
Effect of law and rate changes	0.4		1.9		(68.9)
Change in valuation allowance	(1.8)		(1.6)		(11.4)
State taxes, net of federal benefit	5.1		4.8		4.8
Equity-based compensation	(0.6)		(0.6)		(2.4)
Puerto Rico taxes, net of federal benefit	0.3		2.4		(1.5)
Permanent differences	1.2		1.3		0.5
Federal tax credits, net of reserves	(0.8)		(2.9)		0.3
Other, net	(0.1)		—		0.1
Effective income tax rate	24.7	%	26.3	%	(43.5)	%

Schedule of Deferred Tax Assets and Liabilities

Significant components of deferred income tax assets and liabilities, tax effected, are as follows:

(in millions)	December 31, 2019		December 31, 2018
Deferred tax assets
Loss carryforwards	$	823	$	1,526
Deferred rents	—		784
Lease liability	3,403		—
Reserves and accruals	659		668
Federal and state tax credits	331		340
Other	903		620
Deferred tax assets, gross	6,119		3,938
Valuation allowance	(129)		(210)
Deferred tax assets, net	5,990		3,728
Deferred tax liabilities
Spectrum licenses	5,902		5,494
Property and equipment	2,506		2,434
Lease right-of-use assets	2,881		—
Other intangible assets	19		40
Other	289		232
Total deferred tax liabilities	11,597		8,200
Net deferred tax liabilities	$	5,607	$	4,472
Classified on the balance sheet as:
Deferred tax liabilities	$	5,607	$	4,472

Schedule of Unrecognized Tax Benefits Roll Forward

A reconciliation of the beginning and ending amount of unrecognized tax benefits were as follows:

	Year Ended December 31,
(in millions)	2019		2018		2017
Unrecognized tax benefits, beginning of year	$	462	$	412	$	410
Gross (decreases) increases to tax positions in prior periods	(7)		6		(10)
Gross increases due to current period business acquisitions	—		10		—
Gross increases to current period tax positions	59		34		12
Unrecognized tax benefits, end of year	$	514	$	462	$	412