Pension Plan and Employee Benefits, Unobservable Input Reconciliation (Details) (Pension Benefits [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Fair value of plan assets [Roll Forward]
Fair value of plan assets, end of period	$ 341,892	$ 310,197
Preferred Stock [Member]
Fair value of plan assets [Roll Forward]
Fair value of plan assets, end of period	379	291
Real estate funds [Member]
Fair value of plan assets [Roll Forward]
Fair value of plan assets, end of period	17,341	16,349
Hedge Funds [Member]
Fair value of plan assets [Roll Forward]
Fair value of plan assets, end of period	2,587	2,892
Level 3 [Member]
Fair value of plan assets [Roll Forward]
Fair value of plan assets, beginning of period	19,241	17,839
Realized gain (loss)	2	17
Unrealized gain (loss)	864	1,531
Purchases, issuances, and settlements, net	258	327
Transfer out	(437)	(473)
Fair value of plan assets, end of period	19,928	19,241
Level 3 [Member] \| Preferred Stock [Member]
Fair value of plan assets [Roll Forward]
Fair value of plan assets, end of period	0	0
Level 3 [Member] \| Real estate funds [Member]
Fair value of plan assets [Roll Forward]
Fair value of plan assets, beginning of period	16,349	14,568
Realized gain (loss)	0	0
Unrealized gain (loss)	734	1,454
Purchases, issuances, and settlements, net	258	327
Transfer out	0	0
Fair value of plan assets, end of period	17,341	16,349
Level 3 [Member] \| Hedge Funds [Member]
Fair value of plan assets [Roll Forward]
Fair value of plan assets, beginning of period	2,892	3,271
Realized gain (loss)	2	17
Unrealized gain (loss)	130	77
Purchases, issuances, and settlements, net	0
Transfer out	(437)	(473)
Fair value of plan assets, end of period	$ 2,587	$ 2,892

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Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date, before adjustments for the net liability for pending transactions and interest accrual.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Actual return on plan assets, separately identifying the amount related to assets sold during the period.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph d(iv)(b)(i)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: 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)(A)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(iv)(02)(A)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e2446-114920

+ Details

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- Definition

Actual return on plan assets, separately identifying the amount related to assets still held at the reporting date.

+ References

+ Details

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- Definition

Fair market value amount of assets transferred into (out of) a defined benefit pension plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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- Definition

Purchases, sales, and settlements of plan assets that occurred during the period.

+ 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=21915506&loc=d3e1928-114920

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(iv)(02)(B)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e2446-114920

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph d(iv)(b)(ii)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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