Postretirement Benefits - Estimated Future Payments for Pension Benefits and Other Postretirement Benefit Plans (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Other Benefits [Member]
Pension and Postretirement Benefits [Abstract]
2014	$ 899
2015	1,007
2016	1,130
2017	1,313
2018	1,516
2019-2023	8,227
Pension Benefits [Member]
Pension and Postretirement Benefits [Abstract]
2014	14,973
2015	16,759
2016	18,048
2017	19,847
2018	21,183
2019-2023	$ 129,331

Amount of benefits expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year from a defined benefit plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

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- Definition

Amount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan.

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Amount of benefits expected to be paid in the fifth fiscal year following the latest fiscal year from a defined benefit plan.

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Amount of benefits expected to be paid in the fourth fiscal year following the latest fiscal year from a defined benefit plan.

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Amount of benefits expected to be paid in the third fiscal year following the latest fiscal year from a defined benefit plan.

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Amount of benefits expected to be paid in the second fiscal year following the latest fiscal year from a defined benefit plan.

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