Goodwill and other intangible assets Schedule of Goodwill and Other Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2010
Schedule of Goodwill and Other Intangible Assets [Line Items]
Goodwill, Gross	$ 86,440	$ 348,687
Goodwill Accumulated Amortization and Purchase Price Adjustments	(15,467)	(13,070)
Goodwill	70,973	72,177
Intangible Assets, Impaired, Accumulated Impairment Loss		(218,991)
Goodwill, Impaired, Accumulated Impairment Loss	0	(263,440)
Other intangible assets	12,600	12,600	12,600
Goodwill and Other Intangible Assets, Gross	317,840	582,017
Goodwill and Other Intangible Assets Accumulated Amortization and Purchase Price Adjustments	(15,467)	(14,809)
Other Intangible Assets, Gross		233,330
Other Intangible Assets Accumulated Amorization and Purchase Price Adjustments		(1,739)
Goodwill and Intangible Assets Accumulated Impairment Loss	(218,800)	(482,431)
Goodwill and Intangible Assets Net Carrying Amount	83,573	84,777
Operating segment - Ameristar East Chicago [Member]
Schedule of Goodwill and Other Intangible Assets [Line Items]
Goodwill, Gross		262,247
Goodwill Accumulated Amortization and Purchase Price Adjustments		1,193
Goodwill		0
Acquired Indefinite-lived Intangible Asset, Amount	231,400	231,400
Intangible Assets, Impaired, Accumulated Impairment Loss	(218,800)	(218,800)
Goodwill, Impaired, Accumulated Impairment Loss		(263,440)
Other intangible assets	12,600	12,600
Other Intangible Assets Accumulated Amorization and Purchase Price Adjustments	0	0
Operating Segment - Ameristar Missouri Properties [Member]
Schedule of Goodwill and Other Intangible Assets [Line Items]
Goodwill, Gross	86,435	86,435
Goodwill Accumulated Amortization and Purchase Price Adjustments	(15,467)	(14,263)
Goodwill	70,968	72,172
Goodwill, Impaired, Accumulated Impairment Loss	0	0
Operating segment - Jackpot Properties [Member]
Schedule of Goodwill and Other Intangible Assets [Line Items]
Goodwill, Gross	5	5
Goodwill Accumulated Amortization and Purchase Price Adjustments	0	0
Goodwill	5	5
Goodwill, Impaired, Accumulated Impairment Loss	0	0
Operating segment - Ameristar St. Charles [Member]
Schedule of Goodwill and Other Intangible Assets [Line Items]
Intangible Assets, Impaired, Accumulated Impairment Loss		(191)
Other intangible assets		0
Other Intangible Assets Accumulated Amorization and Purchase Price Adjustments		(109)
Acquired Finite-lived Intangible Asset, Amount		300
Trade Name and Customer List [Member] | Operating segment - Ameristar East Chicago [Member]
Schedule of Goodwill and Other Intangible Assets [Line Items]
Intangible Assets, Impaired, Accumulated Impairment Loss		0
Other intangible assets		0
Other Intangible Assets Accumulated Amorization and Purchase Price Adjustments		(1,630)
Acquired Finite-lived Intangible Asset, Amount		$ 1,630