Revenue - Schedule of Contract Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Contract assets	$ 118.0	$ 121.4
Contract liabilities	41.4	43.4
Net contract assets	76.6	$ 78.0
$ Change
Contract assets	(3.4)
Contract liabilities	(2.0)
Net contract assets	$ (1.4)
% Change
Contract assets	(4.60%)
Contract liabilities	(2.80%)
Net contract assets	(1.80%)