Consolidated Statements of Comprehensive Income (unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Unrealized losses arising during the period, net of tax benefit of $-, $-, $0.2, and $(0.2)	$ 0.0	$ 0.0	$ 0.2	$ 0.2
Reclassification adjustments for losses included in net income, net of tax benefit of $0.1, $1.0, $0.5, and $3.1	0.1	1.0	0.5	3.1
Amortization of net actuarial losses, net of tax benefit of $0.5, $0.5, $1.0, and $1.0	$ 0.5	$ 0.5	$ 1.0	$ 1.0