Income Taxes - Deferred Tax Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Components of Deferred Tax Assets and Liabilities [Abstract]
Workers’ compensation insurance reserve	$ 2.6	$ 3.8
Allowance for doubtful accounts	3.0	2.2
Legal and merger costs	2.7	4.5
Other	7.5	6.9
Less valuation allowance	(15.1)	(17.2)
Total deferred tax assets—current	0.7	0.2
Prepaid expenses	(3.2)	(3.2)
Other	0	(0.2)
Total deferred tax liabilities—current	(3.2)	(3.4)
Net current deferred tax assets (liabilities)	(2.5)	(3.2)
Federal tax credit carry-forwards	28.3	21.2
Federal net operating loss carry-forwards	77.3	71.7
State net operating loss carry-forwards	11.7	9.9
Capital loss carry-forward	6.4	6.5
Los Angeles Revitalization Zone tax credits	0	4.3
Deferred compensation	2.9	4.6
Pre-opening expenses capitalized for tax purposes	10.9	10.1
Unrealized loss on equity securities	(0.4)	(0.3)
Share-based compensation expense—book cost	12.1	16.5
Land, building, riverboats and equipment, net	31.6	45.8
Other	11.2	6.5
Less valuation allowance	(190.3)	(196.3)
Total deferred tax assets—non-current	1.7	0.5
Intangible assets	(5.1)	(4.1)
Total deferred tax liabilities—non-current	(5.1)	(4.1)
Net non-current deferred tax liabilities	(3.4)	(3.6)
Total deferred tax assets	207.7	214.2
Less valuation allowances	(205.4)	(213.4)
Less total deferred tax liabilities	(8.2)	(7.6)
Net deferred tax liabilities	$ (5.9)	$ (6.8)