Fair Value Of Assets And Liabilities (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 27, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	$ 40.1		$ 31.2
Big Fish Games deferred payment	(26.4)	$ 0.0
Long-term debt, net of current maturities and loan origination fees	389.0		632.9
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents and restricted cash			31.2
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	0.0		622.5
Unsecured Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	$ 463.2		$ 496.8
Senior Notes Due 2028 [Member] | Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				4.75%
Revolving Credit Facility [Member] | Line of Credit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 700.0
Secured Debt [Member] | Term Loan B due 2024 [Member] | Line of Credit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Face Amount				$ 400.0