MERGER AND PURCHASE ACCOUNTING (Details) (USD $)	0 Months Ended	9 Months Ended	12 Months Ended
	Sep. 19, 2014	Sep. 18, 2014	Dec. 31, 2014	Dec. 31, 2013
Estimated fair values of the assets acquired and liabilities assumed
Goodwill			$ 66,826,000
Adjusted the preliminary purchase price allocations
Estimated fair values of the assets acquired and liabilities assumed
Property and equipment			19,000,000
Goodwill			37,900,000
Intangible assets			36,400,000
Deferred income taxes			14,600,000
Other noncurrent liabilities			2,000,000
Senior Secured Second Lien Notes
Estimated fair values of the assets acquired and liabilities assumed
Interest rate of debt (as a percent)			11.50%
MTR Gaming
MERGER WITH ELDORADO
Common stock, par value (in dollars per share)	$ 0.00001
Amount of cash election funded	30,000,000
ERI Outstanding Share Calculation
Number of MTR shares outstanding at the Acquisition Date	28,386,084
MTR RSUs that vested upon closing of the Mergers (in shares)	499,179
Ownership interest in combined entity (as a percent)	49.80%
Consideration Transferred (dollars in thousands, except shares and stock price)
Number of MTR shares outstanding at the Acquisition Date	28,386,084,000
MTR RSUs that vested upon closing of the Mergers	499,179,000
Total net MTR shares	23,100,140,000
FMV of MTR common stock at Acquisition Date (in dollars per share)	$ 4.43
MTR Gaming | Senior Secured Second Lien Notes
Estimated fair values of the assets acquired and liabilities assumed
Long-term debt	570,700,000
Interest rate of debt (as a percent)	11.50%
ERI
MERGER WITH ELDORADO
Number of ERI's shares to be received for each outstanding share or vested RSUs of the acquiree's	1
ERI Outstanding Share Calculation
Total ERI shares outstanding - before share repurchase	52,171,465
ERI | MTR Gaming
MERGER WITH ELDORADO
Common stock, par value (in dollars per share)	$ 0.00001
Share price (in dollars per share)	$ 6.05
Amount of cash election funded	35,000,000
ERI Outstanding Share Calculation
Total ERI shares outstanding at Acquisition Date	46,386,342
Eldorado
MERGER WITH ELDORADO
Amount of cash election funded	5,000,000	5,000,000
ERI Outstanding Share Calculation
Ownership interest in combined entity (as a percent)	50.20%
Eldorado | MTR Gaming
ERI Outstanding Share Calculation
MTR shares acquired at $6.05 per share based on $35.0 million cash election	(5,785,123)
Consideration Transferred (dollars in thousands, except shares and stock price)
MTR shares acquired at $6.05 per share based on $35.0 million cash election	(5,785,123,000)
Fair Value of MTR shares	102,334,000
Fair Value of MTR stock options	677,000
Total consideration transferred	103,011,000
Estimated fair values of the assets acquired and liabilities assumed
Current and other assets	75,031,000
Property and equipment	289,211,000
Goodwill	66,826,000
Intangible assets	473,000,000
Other noncurrent assets	20,381,000
Total assets	924,449,000
Current liabilities	46,446,000
Long-term debt	624,877,000
Deferred income taxes	143,104,000
Other noncurrent liabilities	7,011,000
Total liabilities	821,438,000
Net assets acquired	103,011,000
Weighted average useful life	1 year 8 months 12 days
Pro Forma Information
Net revenues			476,045,000	497,791,000
Net loss			$ (6,543,000)	$ (1,818,000)
Eldorado | MTR Gaming | Trade names
Estimated fair values of the assets acquired and liabilities assumed
Useful life	3 years 6 months
Eldorado | MTR Gaming | Customer loyalty programs
Estimated fair values of the assets acquired and liabilities assumed
Useful life	1 year
Eldorado | MTR Gaming | Members of Eldorado
ERI Outstanding Share Calculation
Shares issued to Eldorado (in shares)	23,286,202
Consideration Transferred (dollars in thousands, except shares and stock price)
Number of shares issued were returned to authorized and unissued	25,290