CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Allowance for accounts with partners	$ 7.6	$ 7.6
Allowance for other receivable	$ 1.8	$ 0
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	65,154,195	64,012,914
Treasury stock, shares	7,393,714	7,162,573