Revenue Recognition, Contract Liabilities (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Contract Liabilities
Balance, beginning of period	$ 0
Change in accounting policy - Deferred revenues reclassification	167	[1]
Change in accounting policy - Retained earnings impact	(21)
Contract additions	24
Revenue recognized	(43)
Balance, end of period	$ 127

[1] This amount represents U.S. Cellular's obligation to transfer goods or services to customers for which it had received payment and classified as deferred revenue at December 31, 2017.