Discontinued Operations - Income (Loss) From Discontinued Operations (Details) - Big Fish Games - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
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
Operating expenses	0.0	0.0	0.0	8.4
Selling, general and administrative expense	1.6	0.6	2.0	4.9
Research and development	0.0	0.0	0.0	0.9
Total operating expense	1.6	0.6	2.0	14.2
Operating loss	(1.6)	(0.6)	(2.0)	(1.0)
Other expense	0.0	0.0	0.0	(0.1)
Total other income (expense)	0.0	0.0	0.0	219.4
(Loss) income from discontinued operations before provision for income taxes	(1.6)	(0.6)	(2.0)	218.4
Income tax benefit (provision)	0.4	0.5	0.5	(50.6)
(Loss) income from discontinued operations, net of tax	$ (1.2)	$ (0.1)	$ (1.5)	$ 167.8