CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
CONDENSED CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 1,031.0	$ 887.0
Property and equipment, accumulated depreciation and amortization (in dollars)	4,974.0	4,323.0
Other intangible assets, accumulated amortization (in dollars)	$ 772.0	$ 659.0
Common stock, par value (in dollars per share)	$ 0.05	$ 0.05
Common stock, authorized shares	262,500,000	262,500,000
Common stock, shares issued	148,106,249	146,920,454
Common stock in treasury, shares	48,420,650	48,425,298