Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Amortization of prior service credit, tax	$ 0.0	$ 0.0	$ 0.1	$ 0.1
Amortization of actuarial net losses, tax	$ (0.3)	$ (0.3)	$ (0.6)	$ (0.6)