Write-downs, Reserves, and Project Opening Costs, net of Recoveries - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Divestitures and abandonments charges	$ 59.1	$ 10.1	$ 29.0
Write-down of long-term note receivable	0	0	52.2
Litigation reserves, awards, and settlements	(0.2)	3.2	20.9
Gain on property	11.0	0	0
Hilton Matter [Member]
Litigation reserves, awards, and settlements			25.0
Mississippi [Member]
Divestitures and abandonments charges	28.8	8.3
Potential Joint Venture [Member]
Divestitures and abandonments charges	$ 15.0