Amortizable Intangible Assets (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Amortizable Intangible Assets [Abstract]
Amortization expense for amortizable intangible assets	$ 54,755,000	$ 51,442,000	$ 49,857,000
Amortization expense estimated, 2012	56,337,000
Amortization expense estimated, 2013	55,437,000
Amortization expense estimated, 2014	54,282,000
Amortization expense estimated, 2015	52,949,000
Amortization expense estimated, 2016	$ 48,364,000

The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

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Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during year five of the five succeeding fiscal years.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph a(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16323-109275

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- Definition

The amount of amortization expense expected to be recognized during year four of the five succeeding fiscal years.

+ References

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- Definition

The amount of amortization expense expected to be recognized during year one of the five succeeding fiscal years.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

The amount of amortization expense expected to be recognized during year three of the five succeeding fiscal years.

+ References

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Namespace Prefix:	us-gaap_
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- Definition

The amount of amortization expense expected to be recognized during year two of the five succeeding fiscal years.

+ References

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Data Type:	xbrli:monetaryItemType
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