Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Stockholders' Equity [Abstract]
Dividends per share (in usd per share)	$ 1.38	$ 1.14	$ 0.92
Benefit (expense) for tax, pension and post-retirement liability changes	$ 5.3	$ (25.6)	$ 24.7
Provision (benefit) for tax, derivatives	$ (2.1)	$ (2.3)	$ 1.0