Consolidated Statements of Income and Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Reclassification adjustments to cash flow hedges included in net income, tax	$ 0.6	$ 0.6	$ 1.2	$ 1.1
Amortization of pension and postretirement plans actuarial loss and prior service cost, tax	1.2	1.0	2.3	2.0
Changes in unfunded employee benefit obligations, tax	$ 0.0	$ 2.0	$ 0.0	$ 2.0

Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e640-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph c
-URI http://asc.fasb.org/extlink&oid=84234895&loc=d3e41638-113959

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