Intangible Assets, net and Goodwill - Goodwill (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($) unit	Dec. 31, 2018 USD ($) unit	Dec. 31, 2017 USD ($)
Goodwill [Line Items]
Number of reporting units | unit	9	9
Goodwill
Balance at the beginning of the period	$ 2,956.1	$ 2,956.1	$ 2,888.4
Reporting unit reallocation adjustment		0.0
Acquired goodwill		379.1	14.6
Foreign currency adjustments		(55.3)	53.1
Balance at the end of the period		3,279.9	2,956.1
Gaming
Goodwill
Balance at the beginning of the period	2,475.5	2,475.5	2,428.6
Reporting unit reallocation adjustment		0.0
Acquired goodwill		0.0	0.0
Foreign currency adjustments		(27.0)	46.9
Balance at the end of the period		2,448.5	2,475.5
Accumulated goodwill impairment charges		935.0
Lottery
Goodwill
Balance at the beginning of the period	356.2	356.2	350.0
Reporting unit reallocation adjustment		0.0
Acquired goodwill		0.0	0.0
Foreign currency adjustments		(3.8)	6.2
Balance at the end of the period		352.4	356.2
Accumulated goodwill impairment charges		136.6
Interactive
Goodwill
Balance at the beginning of the period	124.4	124.4	109.8
Reporting unit reallocation adjustment		(124.4)
Acquired goodwill		0.0	14.6
Foreign currency adjustments		0.0	0.0
Balance at the end of the period		0.0	124.4
Social
Goodwill
Balance at the beginning of the period	0.0	0.0	0.0
Reporting unit reallocation adjustment	116.9	116.9
Acquired goodwill		0.0	0.0
Foreign currency adjustments		(1.8)	0.0
Balance at the end of the period		115.1	0.0
Digital
Goodwill
Balance at the beginning of the period	0.0	0.0	0.0
Reporting unit reallocation adjustment	$ 7.5	7.5
Acquired goodwill		379.1	0.0
Foreign currency adjustments		(22.7)	0.0
Balance at the end of the period		$ 363.9	$ 0.0