CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Unrealized net gains arising during period, tax	$ 0	$ 0
Reclassification of net (gains) losses to net income, tax	0.9	0.6
Pension and other postretirement benefit costs arising during period, tax	(0.1)	0
Amortization of pension and other postretirement benefit costs included in net periodic benefit cost, tax	$ 0.3	$ 0.4