XML 47 R1.htm IDEA: XBRL DOCUMENT v3.10.0.1
Document And Entity Information - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2018
Jan. 31, 2019
Jun. 30, 2018
Entity Registrant Name TELEPHONE & DATA SYSTEMS INC /DE/    
Entity Central Index Key 0001051512    
Document Type 10-K    
Document Period End Date Dec. 31, 2018    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 2,000
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY    
Trading Symbol TDS    
Entity Emerging Growth Company false    
Entity Small Business false    
Entity Shell Company false    
Common Shares      
Entity Public Float     2,000
Entity Common Stock, Shares Outstanding   106,539,000  
Series A Common Shares      
Entity Public Float     $ 2
Entity Common Stock, Shares Outstanding   7,284,900