Employee Benefit Plans Net Periodic Costs (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2015
Pension Plan [Member]
Components of Net Periodic Benefit Cost
Service cost	$ 10,830	$ 13,465
Interest cost	26,147	22,719
Recognized actuarial loss	(107,023)	54,671
Settlements	0	0
Net Periodic Costs [Member] \| Pension Plan [Member]
Components of Net Periodic Benefit Cost
Service cost	10,830	13,465	11,488
Interest cost	26,147	22,719	23,823
Expected return on plan assets	(29,506)	(32,491)	(29,996)
Amortization of prior service cost (credit)	246	246	246
Recognized actuarial loss	2,118	11,648	8,646
Settlements	0	0	0
Net Periodic Benefit Cost (Credit)	9,835	15,587	14,207
Net Periodic Costs [Member] \| Other Pension Plan, Postretirement or Supplemental Plans [Member]
Components of Net Periodic Benefit Cost
Service cost	465	541	541
Interest cost	859	877	1,167
Expected return on plan assets	(981)	(1,019)	(1,021)
Amortization of prior service cost (credit)	(1,998)	(1,998)	(1,998)
Recognized actuarial loss	348	1,271	790
Settlements	690	0	0
Net Periodic Benefit Cost (Credit)	(617)	(328)	(521)
Scenario, Forecast [Member] \| Net Periodic Costs [Member] \| Pension Plan [Member]
Components of Net Periodic Benefit Cost
Amortization of prior service cost (credit)				(246)
Scenario, Forecast [Member] \| Net Periodic Costs [Member] \| Other Pension Plan, Postretirement or Supplemental Plans [Member]
Components of Net Periodic Benefit Cost
Amortization of prior service cost (credit)				1,998
Scenario, Forecast [Member] \| Pension Costs [Member] \| Pension Plan [Member]
Components of Net Periodic Benefit Cost
Accumulated gain				(10,470)
Scenario, Forecast [Member] \| Pension Costs [Member] \| Other Pension Plan, Postretirement or Supplemental Plans [Member]
Components of Net Periodic Benefit Cost
Accumulated gain				$ (325)

Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Gain or Loss

-URI http://asc.fasb.org/extlink&oid=6514294

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)(4)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

-Glossary Gain or Loss

-URI http://asc.fasb.org/extlink&oid=6749293

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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.

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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

-URI http://asc.fasb.org/extlink&oid=6512136

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-Topic 715

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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 increase (decrease) in plan assets from purchases, sales and settlement of plan obligations.

+ 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 (d)(iv)(02)(B)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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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

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-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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

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

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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