CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Parenthetical - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss	$ 2.2	$ 1.2	$ 2.4
Net gain (loss) arising during the period	(5.8)	(7.0)	7.8
Settlement (Curtailment) cost	2.9	(0.1)	1.9
Postretirement plans:
Amortization of deferred net loss	0.8	0.5	1.3
Net loss arising during the period	5.6	(1.9)	4.4
Amortization of prior service cost	(1.1)	(1.1)	(1.1)
Deferred commodity contracts hedging (gains) losses reclassified in net income	0.0	0.0	0.4
Amortization of deferred interest rate swap hedging losses	$ 0.0	$ 0.1	$ 0.1