NEW ACCOUNTING STANDARDS - Income Statement Impacts (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Gross revenues	$ 319,500	$ 356,621
Less-Promotional allowances	0	(25,137)
Net revenues	319,500	331,484
Operating costs and expenses:
Selling, general, and administrative	49,018	50,377
Corporate	12,425	12,153
Depreciation and amortization	27,090	20,207
Other, net	1,921	621
Total operating costs and expenses	276,130	276,484
Income from operations	43,370	55,000
Gaming
Revenues:
Gross revenues	221,935	287,006
Operating costs and expenses:
Cost of goods sold	128,664	164,315
Food and beverage
Revenues:
Gross revenues	34,806	21,820
Operating costs and expenses:
Cost of goods sold	26,447	10,189
Hotel
Revenues:
Gross revenues	22,977	14,907
Operating costs and expenses:
Cost of goods sold	9,803	7,005
Retail, entertainment and other
Revenues:
Gross revenues	39,782	32,888
Operating costs and expenses:
Cost of goods sold	20,762	$ 11,617
Balance without Adoption of ASC 606
Revenues:
Gross revenues	346,686
Less-Promotional allowances	(22,737)
Net revenues	323,949
Operating costs and expenses:
Selling, general, and administrative	48,909
Corporate	12,425
Depreciation and amortization	27,090
Other, net	1,921
Total operating costs and expenses	281,893
Income from operations	42,056
Balance without Adoption of ASC 606 | Gaming
Revenues:
Gross revenues	266,328
Operating costs and expenses:
Cost of goods sold	157,026
Balance without Adoption of ASC 606 | Food and beverage
Revenues:
Gross revenues	23,556
Operating costs and expenses:
Cost of goods sold	15,067
Balance without Adoption of ASC 606 | Hotel
Revenues:
Gross revenues	16,815
Operating costs and expenses:
Cost of goods sold	7,048
Balance without Adoption of ASC 606 | Retail, entertainment and other
Revenues:
Gross revenues	39,987
Operating costs and expenses:
Cost of goods sold	12,407
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09
Revenues:
Gross revenues	(27,186)
Less-Promotional allowances	22,737
Net revenues	(4,449)
Operating costs and expenses:
Selling, general, and administrative	109
Corporate	0
Depreciation and amortization	0
Other, net	0
Total operating costs and expenses	(5,763)
Income from operations	1,314
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Gaming
Revenues:
Gross revenues	(44,393)
Operating costs and expenses:
Cost of goods sold	(28,362)
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Food and beverage
Revenues:
Gross revenues	11,250
Operating costs and expenses:
Cost of goods sold	11,380
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Hotel
Revenues:
Gross revenues	6,162
Operating costs and expenses:
Cost of goods sold	2,755
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Retail, entertainment and other
Revenues:
Gross revenues	(205)
Operating costs and expenses:
Cost of goods sold	8,355
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Loyalty Points
Revenues:
Gross revenues	1,219
Less-Promotional allowances	0
Net revenues	1,219
Operating costs and expenses:
Selling, general, and administrative	0
Corporate	0
Depreciation and amortization	0
Other, net	0
Total operating costs and expenses	(95)
Income from operations	1,314
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Loyalty Points | Gaming
Revenues:
Gross revenues	1,219
Operating costs and expenses:
Cost of goods sold	(95)
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Loyalty Points | Food and beverage
Revenues:
Gross revenues	0
Operating costs and expenses:
Cost of goods sold	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Loyalty Points | Hotel
Revenues:
Gross revenues	0
Operating costs and expenses:
Cost of goods sold	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Loyalty Points | Retail, entertainment and other
Revenues:
Gross revenues	0
Operating costs and expenses:
Cost of goods sold	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Promotional Allowances (Discretionary Complementaries)
Revenues:
Gross revenues	(14,485)
Less-Promotional allowances	15,650
Net revenues	1,165
Operating costs and expenses:
Selling, general, and administrative	0
Corporate	0
Depreciation and amortization	0
Other, net	0
Total operating costs and expenses	1,165
Income from operations	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Promotional Allowances (Discretionary Complementaries) | Gaming
Revenues:
Gross revenues	(30,736)
Operating costs and expenses:
Cost of goods sold	(1,711)
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Promotional Allowances (Discretionary Complementaries) | Food and beverage
Revenues:
Gross revenues	10,101
Operating costs and expenses:
Cost of goods sold	2,876
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Promotional Allowances (Discretionary Complementaries) | Hotel
Revenues:
Gross revenues	5,998
Operating costs and expenses:
Cost of goods sold	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Promotional Allowances (Discretionary Complementaries) | Retail, entertainment and other
Revenues:
Gross revenues	152
Operating costs and expenses:
Cost of goods sold	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Promotional Allowances (Non-Discretionary Complementaries)
Revenues:
Gross revenues	(16,242)
Less-Promotional allowances	6,381
Net revenues	(9,861)
Operating costs and expenses:
Selling, general, and administrative	0
Corporate	0
Depreciation and amortization	0
Other, net	0
Total operating costs and expenses	(9,861)
Income from operations	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Promotional Allowances (Non-Discretionary Complementaries) | Gaming
Revenues:
Gross revenues	(17,847)
Operating costs and expenses:
Cost of goods sold	(29,629)
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Promotional Allowances (Non-Discretionary Complementaries) | Food and beverage
Revenues:
Gross revenues	0
Operating costs and expenses:
Cost of goods sold	7,355
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Promotional Allowances (Non-Discretionary Complementaries) | Hotel
Revenues:
Gross revenues	0
Operating costs and expenses:
Cost of goods sold	2,591
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Promotional Allowances (Non-Discretionary Complementaries) | Retail, entertainment and other
Revenues:
Gross revenues	1,605
Operating costs and expenses:
Cost of goods sold	9,822
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Gross vs. Net Presentation and Other
Revenues:
Gross revenues	5,001
Less-Promotional allowances	706
Net revenues	5,707
Operating costs and expenses:
Selling, general, and administrative	109
Corporate	0
Depreciation and amortization	0
Other, net	0
Total operating costs and expenses	5,707
Income from operations	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Gross vs. Net Presentation and Other | Gaming
Revenues:
Gross revenues	5,650
Operating costs and expenses:
Cost of goods sold	5,752
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Gross vs. Net Presentation and Other | Food and beverage
Revenues:
Gross revenues	1,149
Operating costs and expenses:
Cost of goods sold	1,149
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Gross vs. Net Presentation and Other | Hotel
Revenues:
Gross revenues	164
Operating costs and expenses:
Cost of goods sold	164
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Gross vs. Net Presentation and Other | Retail, entertainment and other
Revenues:
Gross revenues	(1,962)
Operating costs and expenses:
Cost of goods sold	(1,467)
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Cash Promotions
Revenues:
Gross revenues	(2,679)
Less-Promotional allowances	0
Net revenues	(2,679)
Operating costs and expenses:
Selling, general, and administrative	0
Corporate	0
Depreciation and amortization	0
Other, net	0
Total operating costs and expenses	(2,679)
Income from operations	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Cash Promotions | Gaming
Revenues:
Gross revenues	(2,679)
Operating costs and expenses:
Cost of goods sold	(2,679)
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Cash Promotions | Food and beverage
Revenues:
Gross revenues	0
Operating costs and expenses:
Cost of goods sold	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Cash Promotions | Hotel
Revenues:
Gross revenues	0
Operating costs and expenses:
Cost of goods sold	0
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09 | Cash Promotions | Retail, entertainment and other
Revenues:
Gross revenues	0
Operating costs and expenses:
Cost of goods sold	$ 0