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Comprehensive Income and Accumulated Other Comprehensive Income (Loss) - Summary of Effects of Reclassifications from Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015
Amortization of pension and other postretirement benefit plan items: |  |
Total net of tax | $ 6,336 | $ 3,430
Settlement loss [Member] |  |
Amortization of pension and other postretirement benefit plan items: |  |
Total before tax | 7,630 |
Actuarial losses [Member] |  |
Amortization of pension and other postretirement benefit plan items: |  |
Total before tax | 2,756 |
Prior service credit [Member] |  |
Amortization of pension and other postretirement benefit plan items: |  |
Total before tax | (84) |
Pension and Other Postretirement Benefit Plans [Member] |  |
Amortization of pension and other postretirement benefit plan items: |  |
Total before tax | 10,302 |
Tax benefit | (3,966) |
Total net of tax | $ 6,336 | $ 3,430

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- Definition Amount before tax of reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669686-108580 + Details
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