Investments and Acquisition Activities (Details) (USD $)	12 Months Ended		3 Months Ended	12 Months Ended									12 Months Ended						12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2013 ACDL game member	Dec. 31, 2012 ACDL Years	Sep. 30, 2012 ACDL	Dec. 31, 2011 ACDL	Sep. 30, 2011 ACDL	Sep. 30, 2010 ACDL	Apr. 02, 2013 Ameristar	Dec. 31, 2012 Ameristar	Dec. 31, 2012 Federated Sports and Gaming	Dec. 31, 2012 Retama Partners	Dec. 31, 2012 Lumiere Place	Dec. 31, 2012 Farmworks	Mar. 31, 2013 Line of Credit ACDL	Dec. 31, 2012 Line of Credit ACDL	Dec. 31, 2012 Retama Partners	Dec. 31, 2012 Corporate Debt Securities	Dec. 31, 2012 Other Assets and Other Accrued Liabilities ACDL	Dec. 31, 2012 Senior Notes Due 2021 [Member] Ameristar
Schedule of Investments and Acquisition Activities
Equity method investment, aggregate cost				$ 111,800,000			$ 95,000,000
Long-term Contract, Number of Guest Rooms			541
Number of table games			90
Number of electronic games			500
Equity Method Investment, Aggregate Cost, Additional Amount				16,800,000
Stock Option Award, Vesting Period				5 years
Equity Method Investment, Capital Raise				67,000,000
Equity method investment, capital raise pro-rata				30,000,000
Capitalized interest costs incurred				8,400,000		3,400,000
Amortization period of intangible asset				50
Options Vested in Period, Fair Value																			300,000
Business Acquisition, Contratual rights												50.00%					50.00%
Line of Credit Facility, Maximum Borrowing Capacity									1,400,000,000	1,400,000,000						175,000,000
Line of Credit Facility, Amount Outstanding															83,700,000
Equity Method Investment Summarized Financial Information, General And Administrative Expenses					9,181,000		7,957,000
Equity Method Investment Summarized Financial Information, Professional Fees					5,498,000		2,654,000
Equity Method Investment Summarized Financial Information, Pre-opening Expenses					4,603,000		0
Equity Method Investment Summarized Financial Information, Interest Expenses					0		4,756,000
Equity Method Investment Summarized Financial Information, Other Expenses					2,726,000		5,051,000
Equity Method Investment Summarized Financial Information, Net Income (Loss) Before Income Taxes					22,008,000		20,418,000
Equity Method Investment Summarized Financial Information, Deferred Income Tax (Recovery) Expense					(837,000)		837,000
Equity Method Investment, Summarized Financial Information, Net Income (Loss)					21,171,000		21,255,000
Equity Method Investment Summarized Financial Information, Comprehensive Income (Loss)					21,171,000		21,255,000
Equity Method Investment Summarized Fnancial Information, Cash and Cash Equivalents					70,786,000		83,560,000
Equity Method Investment Summarized Financial Information, Other Current Assets					8,167,000		7,183,000
Equity Method Investment, Summarized Financial Information, Current Assets					78,953,000		90,743,000
Equity Method Investment Summarized Financial Information Property and Equipment					248,810,000		88,375,000
Equity Method Investment Summarized Financial Information, Intangible Assets, Net					27,561,000		27,396,000
Equity Method Investment, Summarized Financial Information, Noncurrent Assets					16,234,000		7,157,000
Equity Method Investment, Summarized Financial Information, Assets					371,558,000		213,671,000
Equity Method Investment Summarized Financial Information Accounts Payable and Accrued Expenses					61,690,000		19,132,000
Equity Method Investment Summarized Financial Information Long Term Debt, Current Maturities					823,000		0
Equity Method Investment, Summarized Financial Information, Current Liabilities					62,513,000		19,132,000
Equity Method Investment Summarized Financial Information Long Term Debt					80,545,000		0
Equity Method Investment, Summarized Financial Information, Noncurrent Liabilities					8,000		878,000
Equity Method Investment Summarized Financial Information, Redeemable Shares					314,026,000		260,319,000
Equity Method Investment, Summarized Financial Information, Liabilities					457,092,000		280,329,000
Equity Method Investment Summarized Financial Information, Equity					(85,534,000)		(66,658,000)
Equity Method Investment, Summarized Financial Information, Liabilities and Equity					371,558,000		213,671,000
Equity Method Investment Summarized Financial Information Cash Used in Operating Activities					(14,511,000)		(9,997,000)
Equity Method Investment Summarized Financial Information Cash Used in Investing Activities					(125,445,000)		(47,935,000)
Equity Method Investment Summarized Financial Information Cash Provided by Financing Activities					127,168,000		94,998,000
Equity Method Investment Summarized Financial Information Effect of Exchange Rate On Cash And Cash Equivalents					14,000		24,000
Equity Method Investment Summarized Financial Information increase (decrease) in Cash and Cash Equivalents					(12,774,000)		37,090,000
Equity Method Investment Summarized Financial Information Cash At The Beginning Of The Period							83,560,000	46,470,000
Equity Method Investment Summarized Financial Information Cash And Cash Equivalents At The End Of Period					70,786,000		83,560,000
Long-term Purchase Commitment, Amount													50,000,000	2,000,000
Long Term Purchase Commitment, Invesment Credits	13,000,000												10,000,000
Long Term Purchase Commitment, Invested Amount													0
Business Acquisition, Percentage																	75.50%
Long-term Investments												7,800,000
Business Acquisition, Committed Bridge Loan Amount												2,900,000
Business Acquisition, Contingent Consideration, Potential Cash Payment												15,000,000
Cost of Acquired Entity										2,800,000,000	4,600,000
Held-to-maturity securities	4,428,000	0																4,400,000
Held-to-maturity Securities, Noncurrent																		4,500,000
Debt Instrument, Interest Rate, Stated Percentage																				7.50%
Equity Method Investment, Other than Temporary Impairment			$ 92,200,000	$ 25,000,000