Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Consolidated Statements Of Operations [Abstract]
Revenue	$ 1,676	$ 1,933
Operating expenses:
Network access expenses	198	286
Network related expenses	422	444
Selling, general and administrative expenses	408	444
Depreciation and amortization	387	415
Loss on disposal of Northwest Operations		24
Restructuring costs and other charges	2	48
Total operating expenses	1,417	1,661
Operating income	259	272
Investment and other income, net	2	5
Pension settlement costs		(103)
Reorganization items, net	(25)
Interest expense (contractual interest for the three months ended March 31, 2021 was $338 million)	(89)	(383)
Income (loss) before income taxes	147	(209)
Income tax expense (benefit)	87	(23)
Net income (loss)	$ 60	$ (186)
Basic and diluted net earnings (loss) per share attributable to Frontier common shareholders	$ 0.57	$ (1.78)
Total weighted average shares outstanding - basic	104,556	104,363
Total weighted average shares outstanding - diluted	104,896	104,363