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Employment Benefit Plans - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2013 | Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items] |  |
Postretirement and postemployment benefits expense | $ 3,445 | $ 2,099
Unfunded accumulated postretirement benefit obligation | 9,374 |
Assumed health care cost trend rates range | 8.50% |
One percentage point increase on accumulated postretirement benefit obligation | 1,712 |
One percentage point decrease on accumulated postretirement benefit obligation | 536 |
One percentage point increase on accumulated postretirement benefit expense | 1,323 |
One percentage point decrease on accumulated postretirement benefit expense | 399 |
Projected plan benefit obligations | 4.75% | 4.00%
Additional contribution by employer | 100.00% |
Additional to base compensation | 3.00% |
Employee Savings Incentive Plan cost | 1,130 | 1,058
Common stock authorized for awards | 4,000,000 |
Gross stock option expense | 56 | 0
Net income effect from stock options | 56 | 0
Compensation cost, expected weighted average period of recognition | 3 months 29 days |
Shares outstanding, Restricted stock units | 154,186 | 104,389
Shares outstanding, Equity instruments other than options nonvested | 113,921 | 70,530
Shares outstanding, Equity instruments restricted stock units vested | 40,265 | 33,859
Fair value for RSUs vested | 19 | 0
1997 Equity Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Stock granted | 0 | 0
2013 Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Stock granted | 0 |
Awards granted, vesting period to directors | 7 years |
Unvested RSUs granted [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Total unrecognized compensation costs | 2,150 | 0
Compensation cost, expected weighted average period of recognition | 8 months 12 days |
Unvested Stock Options [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Total unrecognized compensation costs | 444 | 0
Additions [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Additional contribution by employer | 50.00% |
Additional to base compensation | 2.00% |
2021 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Assumed health care cost trend rates range | 5.00% |
2013 Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Common stock authorized for awards | 4,000,000 |
Common stock available for future grant | 3,779,146 |
2013 Plan [Member] | Grant Date [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Awards granted, vesting percent | 50.00% |
2013 Plan [Member] | First Anniversary of Grant Date [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Awards granted, vesting percent | 50.00% |
Restricted Stock Units (RSUs) [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Gross restricted stock units expense | 1,051 | 0
Restricted stock units expense, net of tax | $ 1,051 | $ 0

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- Definition The interest rate used to adjust for the time value of money for the plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920 + Details
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- Definition Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (m) -URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920 + Details
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- Definition Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (m) -URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920 + Details
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- Definition The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (m) -URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920 + Details
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- Definition The effect of a one-percentage-point increase in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (m) -URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920 + Details
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- Definition The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (l) -URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Health Care Cost Trend Rate -URI http://asc.fasb.org/extlink&oid=6514820 + Details
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- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942 + Details
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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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