Pension Plan - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014 Participants	Mar. 31, 2014	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Contribution towards pension plan	$ 0			$ 250,000
Recognized pension expense, before income tax		2,909,000
Benefits paid out of pension plan assets to plan participants		10,626,000us-gaap_DefinedBenefitPlanBenefitsPaid
Percentage of benefits paid of total outstanding obligation balance to plan participants		43.00%		43.00%
Number of participants reduced		335
Number of participants reduced percentage		44.00%		44.00%
Net periodic benefit costs, total	$ 75,000		$ 130,000

Defined Benefit Plan Number Of Participants Reduced

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- Definition

Defined Benefit Plan Percentage Of Reduction In Plan Participants

+ References

No definition available.

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- Definition

The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Postretirement Benefits

-URI http://asc.fasb.org/extlink&oid=6521376

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

-Section 50

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Benefits

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- Definition

The increase in the fair value of plan assets from contributions made by the employer.

+ References

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- Definition

Plan assets of a defined benefit plan, as a percentage of projected benefit obligation.

+ References

No definition available.

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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.

+ References

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-Subparagraph (j)

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- Definition

Amount of net gain (loss) recognized in net periodic benefit cost as a result of an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include, but are not limited to, lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contracts to cover vested benefits.

+ References

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

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