Retirement Plans (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets (in hundredths)	7.50%	7.50%
Contribution percentage to defined contribution plan (in hundredths)	100.00%
Pension plan defined benefit plan cost increase limit percentage (in hundredths)	4.00%
Aggregate contributions to the plans	$ 23,356,000	$ 23,158,000	$ 22,427,000
Seafarers Pension Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension contributions	$ 1,290,000	$ 1,368,000
Contribution percentage to defined contribution plan (in hundredths)	100.00%
Maximum contribution limit (in hundredths)	5.00%

Represents maximum entity's contribution limit to the concerned pension trust during the reporting period.

No definition available.

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- Definition

Defined Contribution Plan Contribution Percentage.

+ References

No definition available.

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- Definition

Pension Plan Defined Benefit Plan Cost Increase Limit Percentage

+ References

No definition available.

+ Details

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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Expected Long-Term Rate of Return on Plan Assets

-URI http://asc.fasb.org/extlink&oid=6512013

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(3)

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

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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

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- Definition

The amount of cash or cash equivalents contributed by the entity to fund its pension plans.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

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