UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 6.7	$ 13.2
Intangible Assets, accumulated amortization	$ 1,124.6	$ 1,050.0
Common units [Member]
Limited partners:
Capital account, units outstanding (in units)	924,770,538	898,813,337
Class B units [Member]
Limited partners:
Capital account, units outstanding (in units)		4,520,431