Fair Value Disclosure (Details Textual) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2012	Dec. 31, 2011
Fair Value Disclosure (Textual) [Abstract]
Aggregate notional amount of outstanding Fair value hedge derivative instruments	$ 350.0	$ 350.0
Aggregate notional amount of outstanding Cash flow hedge derivative instruments	71.7	73.4
Aggregate fair value of all derivative instruments with Net liability position	1.6
Expected Pre tax reclassification of net losses from accumulated other comprehensive income to earnings in Next Twelve Months	6.9
Expected After tax reclassification of net losses from accumulated other comprehensive income to earnings in Next Twelve Months	$ 4.4
Fair Value Hedging [Member]
Derivative (Textual) [Abstract]
No. of instruments, outstanding	3	3
Maturity date range of hedge derivatives	2012-2015
Fair value hedges lower maturity period	1 year 6 months 15 days
Fair value hedges higher remaining period	3 years 6 months 15 days
Cash Flow Hedging [Member]
Derivative (Textual) [Abstract]
No. of instruments, outstanding	11	11
Maturity date range of hedge derivatives	2012-2014

Cash flow hedge pre-tax gain (loss) to be reclassified within twelve months.

No definition available.

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- Definition

Maturity date range of derivative instruments.

+ References

No definition available.

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The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80748-113994

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 45

-Subparagraph b(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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- Definition

High end period remaining until maturity for the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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Low end period remaining until maturity of derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (c)

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-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44D

-Subparagraph b

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- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

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Aggregate notional amount of all derivatives designated as cash flow hedging instruments. The notional amount relates to a number of currency units, shares, bushels, pounds, or other units specified in a derivative instrument.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

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- Definition

Aggregate notional amount of all interest rate derivatives designated as hedging instruments in fair value hedges. Notional amount refers to the monetary amount specified in the interest rate derivative contract.

+ References

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