CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Accounts receivable, allowances	$ 27.2	$ 27.5
Property and equipment, accumulated depreciation	$ 560.5	$ 518.9
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Common stock, shares authorized	1,000,000,000	1,000,000,000
Treasury stock, shares	150,647,727	146,826,744
Series common stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	10,000,000	10,000,000
Common Stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	342,902,272	342,902,272