INCOME TAXES - Federal Tax Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of federal income taxes at the applicable statutory rate to the recorded provision from continuing operations
Federal statutory rate	21.00%	21.00%	35.00%
Adjustments:
Federal tax credits	(684.60%)	(19.90%)	(2.20%)
Spectrum sales	(386.70%)	(5.80%)	0.00%
Valuation allowance	(237.10%)	0.70%	0.00%
Nondeductible items	192.70%	0.40%	1.70%
Noncontrolling interest	(138.90%)	(0.30%)	(0.80%)
Changes in unrecognized tax benefits	72.20%	0.00%	0.50%
State income taxes, net of federal tax benefit	56.60%	(8.80%)	5.20%
Effect of consolidated VIEs	46.30%	1.60%	1.00%
Capital loss carryback	(26.00%)	0.00%	0.00%
Stock-based compensation	(15.90%)	0.50%	(0.20%)
Federal tax reform	0.00%	(1.40%)	(54.30%)
Other	(3.00%)	0.30%	(1.00%)
Effective income tax rate	(1103.40%)	(11.70%)	(15.10%)
Investment tax credits	$ 57	$ 58	$ 8
Spectrum sales	34	18
Valuation allowance	16
Nondeductible items	19
Noncontrolling interest	12
Change in unrecognized tax benefits	4
Capital loss carryback	$ 2
Federal tax reform		$ 4	$ 272