Employee Benefit Plans (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Components of net periodic cost:
Service cost	$ 6,523us-gaap_DefinedBenefitPlanServiceCost	$ 7,476us-gaap_DefinedBenefitPlanServiceCost
Interest cost	26,170us-gaap_DefinedBenefitPlanInterestCost	23,957us-gaap_DefinedBenefitPlanInterestCost
Defined Benefit Pension Plan
Expected benefit payments for the Defined Benefit Pension, Post-Retirement Medical and Supplemental Executive Retirement plans
2015	15,670
2016	17,102
2017	18,192
2018	19,891
2019	21,285
2020 through 2024	135,763
Components of net periodic cost:
Service cost	4,952	5,527	4,350
Interest cost	23,068	20,897	20,945
Expected return on plan assets	(29,288)	(24,499)	(21,797)
Amortization of unrecognized prior service cost	51	51	51
Amortization of loss from earlier periods	2,898	16,001	9,941
Net periodic cost	1,681	17,977	13,490
Post-Retirement Medical Plan
Expected benefit payments for the Defined Benefit Pension, Post-Retirement Medical and Supplemental Executive Retirement plans
2015	606
2016	547
2017	556
2018	569
2019	625
2020 through 2024	4,171
Components of net periodic cost:
Service cost	985	947	817
Interest cost	574	512	569
Amortization of unrecognized prior service cost	(1,706)	(1,650)	(1,650)
Amortization of loss from earlier periods	(450)	(348)	(455)
Net periodic cost	(597)	(539)	(719)
Supplemental Executive Retirement Plan
Expected benefit payments for the Defined Benefit Pension, Post-Retirement Medical and Supplemental Executive Retirement plans
2015	4,874
2016	3,322
2017	3,306
2018	2,834
2019	2,518
2020 through 2024	15,883
Components of net periodic cost:
Service cost	586	1,002	991
Interest cost	2,528	2,548	2,912
Amortization of unrecognized prior service cost	4,844	933	934
Amortization of loss from earlier periods	282	1,299	637
Settlement	1,857	0	0
Net periodic cost	$ 10,097	$ 5,782	$ 5,474

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

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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.

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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.

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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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- 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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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

-Glossary Expected Return on Plan Assets

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)(3)

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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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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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Section 15

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=7577095&loc=d3e8001-114927

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-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)(7)

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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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)(1)

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-Publisher FASB

-Name Accounting Standards Codification

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

-URI http://asc.fasb.org/extlink&oid=6525008

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)(1)

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

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