Stock-Based Compensation (Performance Share Units) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for PSU grants		range from 24 to 36 months
Maximum [Member] \| Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target award of PSUs, percentage		200.00%
Minimum [Member] \| Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target award of PSUs, percentage		0.00%
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 336	$ 697
Per share weighted average grant date fair value stock options		$ 24.38
Nonvested share units at beginning of period, number of share units
Granted, number of share units		109,375
Performance criteria adjustment, number of share units	31,127	31,127
Forfeited, number of share units		(2,039)
Vested, number of share units
Share unit awards issued, number of share units
Nonvested share units at end of period, number of share units	138,463	138,463
Nonvested share units at beginning of period, weighted average fair value
Granted, weighted average fair value		$ 24.38
Performance criteria adjustment, weighted average fair value	$ 24.38	$ 24.38
Forfeited, weighted average fair value	$ 24.38	$ 24.38
Vested, weighted average fair value
Share unit awards issued, weighted average fair value
Nonvested share units at end of period, weighted average fair value	$ 24.38	$ 24.38

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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-Section 50

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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph g(1)

-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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section S99

-Paragraph 1

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-URI http://asc.fasb.org/extlink&oid=6793087&loc=d3e301413-122809

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section F

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64

-Subparagraph b

-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.