Components of Net Pension Costs (Detail) (Pension Plans, USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned during the year	$ 6,249	$ 5,606	$ 12,497	$ 11,212
Interest cost on accumulated benefit obligation	3,991	3,700	7,982	7,400
Expected return on assets	(3,751)	(3,027)	(7,501)	(6,054)
Net amortization of unrecognized amounts, Prior service cost	1,560	1,498	3,121	2,996
Curtailment loss	7,776		7,776
Net amortization of unrecognized amounts, Actuarial loss	1,502	1,229	3,003	2,458
Net Benefit Costs	$ 17,327	$ 9,006	$ 26,878	$ 18,012

The amount of gains or losses recognized in net periodic benefit cost.

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- Definition

The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

+ References

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- Definition

The amount of decrease that is related to an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Plan Curtailment

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- Definition

An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Expected Return on Plan Assets

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- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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- Definition

The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

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- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

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-Publisher FASB

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-Glossary Service Cost (Component of Net Periodic Pension Cost)

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