Consolidated Statements of Income and Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Reclassification adjustments to cash flow hedges included in net income, net of tax of $0.5 million, $0.5 million, $1.6 million, and $1.6 million	$ 500	$ 500	$ (1,600)	$ (1,600)
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $1.0 million, $1.4 million, $3.1 million, and $4.2 million	1,000	1,400	(3,100)	(4,200)
Changes in unfunded employee benefit obligation net of tax of $2.0 million	$ 0	$ 0	$ 2,000	$ 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=66004124&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=64837297&loc=d3e41638-113959

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