Summary of Significant Accounting Policies - Concentration of Risk (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Concentration of Credit Risk
Receivables	$ 62,805	$ 61,855
Receivables | Credit Concentration Risk | Casino Rama and Hollywood Casino Jamul-San Diego
Concentration of Credit Risk
Receivables	9,900	11,800
Receivables | Credit Concentration Risk | Hollywood Casino At Penn National Race Course
Concentration of Credit Risk
Receivables	5,500	4,000
Receivables | Credit Concentration Risk | Kansas Entertainment
Concentration of Credit Risk
Receivables	3,400	3,400
Receivables | Credit Concentration Risk | Approved casino marker customers
Concentration of Credit Risk
Receivables	3,700	4,400
Receivables | Credit Concentration Risk | West Virginia Lottery | Hollywood Casino at Charles Town Races
Concentration of Credit Risk
Receivables	6,100	5,000
Receivables | Credit Concentration Risk | Customers receiving cash, credit card, and other advances
Concentration of Credit Risk
Receivables	13,900	10,800
Receivables | Credit Concentration Risk | Social casino game revenue platform providers
Concentration of Credit Risk
Receivables	$ 3,000	$ 3,200