Summary of Significant Accounting Policies (Details) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended		9 Months Ended			3 Months Ended				9 Months Ended				3 Months Ended		9 Months Ended																		3 Months Ended				9 Months Ended						3 Months Ended				9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Other Properties		Sep. 30, 2013 Other Properties		Sep. 30, 2014 Other Properties		Sep. 30, 2013 Other Properties		Sep. 30, 2014 Antidilutive securities	Sep. 30, 2013 Antidilutive securities	Sep. 30, 2014 Antidilutive securities	Sep. 30, 2013 Antidilutive securities	Sep. 30, 2014 Estimate of Fair Value Measurement [Member] Fair Value, Measurements, Recurring	Dec. 31, 2013 Estimate of Fair Value Measurement [Member] Fair Value, Measurements, Recurring	Sep. 30, 2014 Estimate of Fair Value Measurement [Member] Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2013 Estimate of Fair Value Measurement [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Recurring	Dec. 31, 2013 Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Recurring	Sep. 30, 2014 Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring	Sep. 30, 2014 Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2014 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring	Sep. 30, 2014 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2013 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2014 Ameristar		Sep. 30, 2013 Ameristar		Sep. 30, 2014 Ameristar	Sep. 30, 2013 Ameristar	Aug. 12, 2013 Ameristar	Sep. 30, 2014 Credit Facility	Dec. 31, 2013 Credit Facility	Dec. 31, 2013 Ameristar	Sep. 30, 2014 Belterra Park [Member]		Sep. 30, 2013 Belterra Park [Member]		Sep. 30, 2014 Belterra Park [Member]		Sep. 30, 2013 Belterra Park [Member]
Costs Associated With REIT Spin Off	$ 900,000
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)			0	10,000,000
Indefinite-Lived Intangible Assets (Excluding Goodwill)																																												50,000,000				50,000,000
Payments to Acquire Intangible Assets			25,000,000	0																																								25,000,000
Deferred Compensation																		600,000	800,000			600,000	800,000			0	0			0	0
Held-to-maturity Securities	14,800,000		14,800,000		14,800,000
Held-to-maturity Securities, Fair Value																				30,100,000	30,100,000			0	0			26,700,000	26,700,000			3,400,000	3,400,000
Promissory Notes	11,500,000		11,500,000		9,500,000
Promissory Notes, Fair Value																				18,500,000	16,500,000			0	0			18,500,000	16,484,000			0	0
Long-term Debt	3,993,300,000		3,993,300,000		4,380,100,000																																			1,112,897,000	565,000,000	493,618,000
Long-term Debt, Fair Value																				4,066,800,000	4,511,900,000			0	0			4,066,800,000	4,511,900,000			0	0
Land Not Used In Operations	35,700,000		35,700,000
Land and land improvements	391,700,000		391,700,000		391,700,000																																			162,770,000
Buildings, vessels and improvements	2,649,800,000		2,649,800,000		2,492,200,000																																			1,308,151,000
Furniture, fixtures and equipment	693,500,000		693,500,000		633,100,000																																			158,999,000
Construction in Progress	118,500,000		118,500,000		175,600,000																																			153,815,000
Land, buildings, vessels and equipment, gross	3,853,500,000		3,853,500,000		3,692,600,000
Less: accumulated depreciation	(809,200,000)		(809,200,000)		(656,100,000)
Customer Loyalty Program Liability	26,300,000		26,300,000		18,900,000																																						12,800,000
Complimentary Revenues, Food and Beverage	35,200,000	28,100,000	102,100,000	61,700,000
Complimentary Revenues, Lodging	15,400,000	14,900,000	46,600,000	29,300,000
Complimentary Revenues, Other	4,900,000	3,700,000	13,000,000	9,300,000
Total promotional allowances	55,500,000	46,700,000	161,700,000	100,300,000
Promotional allowance costs included in gaming expense	42,100,000	31,800,000	119,400,000	72,200,000
Gaming taxes	142,100,000	105,300,000	416,400,000	244,100,000
Pre-opening, development and other costs	1,598,000	63,086,000	11,917,000	87,851,000		1,000,000	[1]	500,000	[1]	1,500,000	[1]	1,400,000	[1]																					(200,000)	[2]	62,300,000	[2]	2,200,000	86,000,000					800,000	[3]	300,000	[3]	8,200,000	[3]	500,000	[3]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount														1.8	1.9	1.5	1.6
Property, Plant and Equipment, Net	3,044,296,000		3,044,296,000		3,036,515,000																																			1,783,735,000
Accrued Payment to Acquire Intangible Assets			$ (25,000,000)	$ 0																																												$ 25,000,000

[1] (3)Includes $0.9 million of cost associated with our evaluation of a REIT spin-off transaction.

[2] (1)Amounts principally comprised of legal and advisory expenses, severance charges and other costs and expenses related to the financing and integration of the acquisition of Ameristar.

[3] (2)Belterra Park opened on May 1, 2014.