Revenue Recognition, Contract Liabilities (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Contract Liabilities
Balance at December 31, 2017	$ 0
Change in accounting policy - Deferred revenues reclassification	167	[1]
Change in accounting policy - Retained earnings impact	(21)
Contract additions	53
Revenue recognized	(74)
Balance at June 30, 2018	$ 125

[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.