Discontinued Operations - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
	Jan. 09, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Distributions of capital from unconsolidated affiliates					$ 0.0	$ 970.7
Carrying value of Big Fish Games				$ 751.2
Income tax provision on gain from sale of business				51.2
After tax gain				168.3
Stock-based compensation		$ 5.5	$ 3.9		17.6	16.5
Gain (Loss) on Disposition of Business				219.5	0.0	219.5
Gain on sale of Big Fish Games				970.7
Income tax provision on gain from sale of business				51.2
After tax gain				168.3
Gain (Loss) on Disposition of Business				$ 219.5	0.0	219.5
Big Fish Games
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net revenue		0.0	0.0		0.0	13.2
Stock-based compensation						3.4
Operating expenses		0.0	0.0		0.0	8.4
Selling, general and administrative expense		0.8	0.7		2.8	5.6
Research and development		0.0	0.0		0.0	0.9
Total operating expense		0.8	0.7		2.8	14.9
Operating loss		(0.8)	(0.7)		(2.8)	(1.7)
Gain (Loss) on Disposition of Business		0.0	0.0		0.0	219.5
Disposal Group, Including Discontinued Operation, Other Expense		0.0	0.0		0.0	0.1
Total other income		0.0	0.0		0.0	219.4
(Loss) income from discontinued operations before provision for income taxes		(0.8)	(0.7)		(2.8)	217.7
Discontinued Operation, Tax Effect of Income (Loss) from Discontinued Operation During Phase-out Period		(0.4)	1.0		(0.9)	51.6
(Loss) income from discontinued operations, net of tax		(0.4)	(1.7)		(1.9)	166.1
Gain (Loss) on Disposition of Business		$ 0.0	$ 0.0		$ 0.0	$ 219.5
Big Fish Games | Earnout Liability
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Earnout liability							$ 34.2
Big Fish Games | Deferred Payments
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Earnout liability							$ 28.4
Discontinued Operations, Disposed of by Sale | Big Fish Games
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase price	$ 990.0
Distributions of capital from unconsolidated affiliates	970.7
Working capital adjustments	5.2
Transaction expense, net	14.1
Carrying value of Big Fish Games	$ 751.2