Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Millions		6 Months Ended
	May 17, 2018	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividends per share common stock (in dollars per share)	$ 0.16	$ 0.32	$ 0.32
Reduction to retained earnings		$ (1,593.2)			$ (1,735.2)
ASU 2016-16
Reduction to retained earnings				$ 1.0
ASU 2014-09
Reduction to retained earnings				$ (2.4)