DISCONTINUED OPERATIONS - SALE OF U.S. RETAIL WIRELESS BUSINESS (Details) - Alltel Sale - AT&T Mobility - USD ($) $ in Millions		12 Months Ended
	Sep. 20, 2013	Dec. 31, 2015	Dec. 31, 2014
Liabilities sold:
Additional gain (loss) on sale of assets		$ 1.1	$ 1.1
Alltel Wireless
SALE OF U.S. RETAIL WIRELESS BUSINESS
Consideration for sale of operations in all-cash transaction	$ 780.0
Proceeds:
Working capital	$ 16.8