Summary of Significant Accounting Policies (Details) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended																	3 Months Ended				6 Months Ended						3 Months Ended				6 Months Ended				3 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Other Properties	Jun. 30, 2013 Other Properties	Jun. 30, 2014 Other Properties	Jun. 30, 2013 Other Properties	Jun. 30, 2014 Antidilutive securities	Jun. 30, 2014 Antidilutive securities	Jun. 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	Jun. 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]	Jun. 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	Jun. 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]	Jun. 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	Jun. 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]	Jun. 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	Jun. 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]	Jun. 30, 2014 Ameristar		Jun. 30, 2013 Ameristar		Jun. 30, 2014 Ameristar	Jun. 30, 2013 Ameristar	Aug. 12, 2013 Ameristar	Jun. 30, 2014 Credit Facility	Dec. 31, 2013 Credit Facility	Dec. 31, 2013 Ameristar	Jun. 30, 2014 Belterra Park [Member]		Jun. 30, 2013 Belterra Park [Member]		Jun. 30, 2014 Belterra Park [Member]		Jun. 30, 2013 Belterra Park [Member]		Jun. 30, 2014 Lumiere Place [Member]
Disposal Group, Divestiture of Business, Purchase price, Net																																														$ 252,300,000
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	26,676,000			3,400,000	3,438,000
Promissory Notes	10,700,000		10,700,000		9,500,000
Promissory Notes, Fair Value														17,600,000	16,500,000			0	0			17,600,000	16,484,000			0	0
Long-term Debt	4,109,500,000		4,109,500,000		4,380,100,000																													1,112,897,000	573,618,000	493,618,000
Long-term Debt, Fair Value														4,272,300,000	4,511,900,000			0	0			4,272,300,000	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	2,633,600,000		2,633,600,000		2,492,200,000																													1,308,151,000
Furniture, fixtures and equipment	691,700,000		691,700,000		633,100,000																													158,999,000
Construction in Progress	109,400,000		109,400,000		175,600,000																													153,815,000
Land, buildings, vessels and equipment, gross	3,826,400,000		3,826,400,000		3,692,600,000
Less: accumulated depreciation	(757,600,000)		(757,600,000)		(656,100,000)
Customer Loyalty Program Liability	32,700,000		32,700,000		18,900,000																																12,800,000
Complimentary Revenues, Food and Beverage	33,700,000	17,200,000	66,900,000	33,600,000
Complimentary Revenues, Lodging	15,100,000	7,500,000	31,100,000	14,400,000
Complimentary Revenues, Other	4,400,000	2,900,000	8,200,000	5,600,000
Total promotional allowances	53,200,000	27,600,000	106,200,000	53,600,000
Promotional allowance costs included in gaming expense	39,300,000	19,993,000	77,400,000	40,400,000
Gaming taxes	141,500,000	68,700,000	274,300,000	138,800,000
Pre-opening and development costs	6,907,000	17,212,000	10,319,000	24,765,000		200,000	500,000	500,000	1,200,000																			2,000,000	[1]	16,600,000	[1]	2,400,000	23,300,000					4,700,000	[2]	100,000	[2]	7,400,000	[2]	300,000	[2]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1.9	1.6		1.4						1.4	1.3
Property, Plant and Equipment, Net	3,068,828,000		3,068,828,000		3,036,515,000																													1,783,735,000
Accrued Payment to Acquire Intangible Assets			25,000,000	0																																						25,000,000
Cash Divested from Deconsolidation																																														$ 11,000,000

[1] (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.

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