Significant Accounting Policies - Revenue Disaggregation and Customer-Related Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 1,323,094	$ 826,913	$ 2,605,665	$ 1,642,998
Loyalty credit obligation
Disaggregation of Revenue [Line Items]
Customer-related liabilities	49,000		$ 49,000		$ 39,900
Customer-related liabilities, term			6 months
Advance payments on goods and services yet to be provided and unpaid wagers
Disaggregation of Revenue [Line Items]
Customer-related liabilities	30,700		$ 30,700		34,300
Customer-related liabilities, long-term	600		600		$ 700
Gaming
Disaggregation of Revenue [Line Items]
Revenues	1,062,139	665,094	2,096,650	1,319,588
Food and beverage
Disaggregation of Revenue [Line Items]
Revenues	126,704	64,737	251,898	128,380
Hotel
Disaggregation of Revenue [Line Items]
Revenues	80,242	35,282	151,651	68,803
Racing
Disaggregation of Revenue [Line Items]
Revenues	8,604	6,650	16,680	13,461
Reimbursable management costs
Disaggregation of Revenue [Line Items]
Revenues		25,187		53,371
Other
Disaggregation of Revenue [Line Items]
Revenues	45,405	29,963	88,786	59,395
Operating segments | Northeast segment
Disaggregation of Revenue [Line Items]
Revenues	599,086	465,285	1,149,664	924,004
Operating segments | Northeast segment | Gaming
Disaggregation of Revenue [Line Items]
Revenues	528,906	398,719	1,016,633	790,997
Operating segments | Northeast segment | Food and beverage
Disaggregation of Revenue [Line Items]
Revenues	37,584	23,321	73,381	46,624
Operating segments | Northeast segment | Hotel
Disaggregation of Revenue [Line Items]
Revenues	10,498	5,316	17,652	10,036
Operating segments | Northeast segment | Racing
Disaggregation of Revenue [Line Items]
Revenues	6,987	4,890	13,512	10,167
Operating segments | Northeast segment | Reimbursable management costs
Disaggregation of Revenue [Line Items]
Revenues		21,068		42,912
Operating segments | Northeast segment | Other
Disaggregation of Revenue [Line Items]
Revenues	15,111	11,971	28,486	23,268
Operating segments | South segment
Disaggregation of Revenue [Line Items]
Revenues	282,188	62,618	574,130	125,948
Operating segments | South segment | Gaming
Disaggregation of Revenue [Line Items]
Revenues	206,841	49,213	426,932	100,189
Operating segments | South segment | Food and beverage
Disaggregation of Revenue [Line Items]
Revenues	39,551	8,657	79,741	17,087
Operating segments | South segment | Hotel
Disaggregation of Revenue [Line Items]
Revenues	26,521	3,119	49,501	5,599
Operating segments | South segment | Racing
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Operating segments | South segment | Reimbursable management costs
Disaggregation of Revenue [Line Items]
Revenues		0		0
Operating segments | South segment | Other
Disaggregation of Revenue [Line Items]
Revenues	9,275	1,629	17,956	3,073
Operating segments | West segment
Disaggregation of Revenue [Line Items]
Revenues	164,250	100,751	322,904	198,717
Operating segments | West segment | Gaming
Disaggregation of Revenue [Line Items]
Revenues	96,498	50,550	189,321	97,121
Operating segments | West segment | Food and beverage
Disaggregation of Revenue [Line Items]
Revenues	29,548	20,967	57,418	40,816
Operating segments | West segment | Hotel
Disaggregation of Revenue [Line Items]
Revenues	31,631	20,900	63,272	42,021
Operating segments | West segment | Racing
Disaggregation of Revenue [Line Items]
Revenues	84	99	101	106
Operating segments | West segment | Reimbursable management costs
Disaggregation of Revenue [Line Items]
Revenues		4,119		10,459
Operating segments | West segment | Other
Disaggregation of Revenue [Line Items]
Revenues	6,489	4,116	12,792	8,194
Operating segments | Midwest segment
Disaggregation of Revenue [Line Items]
Revenues	268,160	188,162	539,422	373,696
Operating segments | Midwest segment | Gaming
Disaggregation of Revenue [Line Items]
Revenues	229,889	166,612	463,644	331,281
Operating segments | Midwest segment | Food and beverage
Disaggregation of Revenue [Line Items]
Revenues	19,624	11,473	40,662	23,271
Operating segments | Midwest segment | Hotel
Disaggregation of Revenue [Line Items]
Revenues	11,592	5,947	21,226	11,147
Operating segments | Midwest segment | Racing
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Operating segments | Midwest segment | Reimbursable management costs
Disaggregation of Revenue [Line Items]
Revenues		0		0
Operating segments | Midwest segment | Other
Disaggregation of Revenue [Line Items]
Revenues	7,055	4,130	13,890	7,997
Other
Disaggregation of Revenue [Line Items]
Revenues	9,410	10,097	19,545	20,633
Other | Gaming
Disaggregation of Revenue [Line Items]
Revenues	5	0	120	0
Other | Food and beverage
Disaggregation of Revenue [Line Items]
Revenues	397	319	696	582
Other | Hotel
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Other | Racing
Disaggregation of Revenue [Line Items]
Revenues	1,533	1,661	3,067	3,188
Other | Reimbursable management costs
Disaggregation of Revenue [Line Items]
Revenues		0		0
Other | Other
Disaggregation of Revenue [Line Items]
Revenues	$ 7,475	$ 8,117	$ 15,662	$ 16,863