Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Consolidated Statements Of Operations [Abstract]
Revenue	$ 1,539	$ 1,480	$ 3,050	$ 2,942
Operating expenses:
Cost of service	532	516	1,053	1,038
Selling, general, and administrative expenses	490	449	923	877
Depreciation and amortization	457	398	902	786
Restructuring costs and other charges	16	26	52	60
Total operating expenses	1,495	1,389	2,930	2,761
Operating income	44	91	120	181
Investment and other income (loss), net (See Note 11)	14	(24)	63	88
Interest expense	(197)	(199)	(397)	(398)
Loss before income taxes	(139)	(132)	(214)	(129)
Income tax benefit	(16)	(9)	(27)	(7)
Net loss	$ (123)	$ (123)	$ (187)	$ (122)
Basic net loss per share attributable to Frontier common shareholders	$ (0.49)	$ (0.49)	$ (0.75)	$ (0.49)
Diluted net loss per share attributable to Frontier common shareholders	$ (0.49)	$ (0.49)	$ (0.75)	$ (0.49)
Total weighted average shares outstanding - basic	250,259	248,754	250,019	247,382
Total weighted average shares outstanding - diluted	250,259	248,754	250,019	247,382