Additional Financial Information (Supplemental Statements of Cash Flows Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Additional Financial Information [Abstract]
Interest payments, net of amounts capitalized	$ 1,298	$ 1,367	$ 1,156
Income tax payments	54	36	20
Increase in accounts payable for purchases of property and equipment	46	402	6
Leased wireless devices transferred from inventory to property and equipment, net of returns	2,285	0	0
Issuance of short-term debt for financing of property and equipment purchases	500	256	470
Assets acquired under capital lease obligations	470	77	3
Retirement of long-term debt to affiliates	0	0	14,450
Elimination of net unamortized discounts and premiums on long-term debt to affiliates	0	0	434
Issuance of new long-term debt to affiliates	0	0	11,200
Settlement of accounts receivable from affiliates and other outstanding balances	0	0	363
Income tax benefit from debt recapitalization	0	0	178
Net assets acquired in MetroPCS business combination, excluding cash acquired	$ 0	$ 0	$ 827