UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 13.9	$ 12.4
Intangible assets, accumulated amortization	$ 1,763.7	$ 1,687.5
Limited partners:
Common units issued (in units)	2,240,703,785	2,189,226,130
Common units outstanding (in units)	2,185,896,433	2,189,226,130
Treasury units outstanding (in units)	54,807,352