Summary of Significant Accounting Policies - Land, Buildings, Riverboats and Equipment (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Property, Plant and Equipment [Line Items]
Land not used in operations	$ 30.3	$ 34.9
Depreciation expense	$ 103.7	$ 109.6	$ 95.2
Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	5
Estimated useful life, maximum	35
Building and Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	15
Estimated useful life, maximum	35
Vessels [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	10
Estimated useful life, maximum	25
Furniture and Fixtures and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life, minimum	3
Estimated useful life, maximum	20