Mortgage (Details Textual) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
Jun. 30, 2012 Buildings Facilities	Dec. 31, 2011
Mortgage (Textual) [Abstract]
Mortgage loan term	10 years
Distribution facilities	52
Number of office building owned by special purpose	1
Mortgage interest rate	6.35%
Payment of indebtedness under the mortgage	$ 38.3
Amount expected to be transferred to the cash trap during the next twelve months	10.8
Debt fees	2.9
Previous ownership percentage required by the Mortgage Lender removed by amendment	51.00%
Increase in restricted cash in 2012	0.3	6.5
Restricted cash used to reduce the mortgage principal	6.5
Mortgage [Member]
Debt Instrument [Line Items]
Mortgage loan	$ 295

Amount expected to be transferred to cash trap during next twelve months.

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- Definition

Mortgage loan secured by number of distribution facilities

+ References

No definition available.

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- Definition

Mortgage loan secured by number of office building.

+ References

No definition available.

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- Definition

Mortgage loan term period.

+ References

No definition available.

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- Definition

Prepayments of indebtedness under the mortgage.

+ References

No definition available.

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- Definition

Previous ownership percentage required by the mortgage lender removed by amendment.

+ References

No definition available.

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- Definition

Restricted cash used to reduce mortgage principal.

+ References

No definition available.

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- Definition

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number APB14-1

-Paragraph 31

-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.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section S99

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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher SEC

-Name Regulation S-X (SX)

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-Section 02

-Paragraph 22

-Article 5

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- Definition

Amount of the fee that accompanies borrowing money under the debt instrument.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Interest rate stated in the contractual debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

The net cash inflow or outflow for the increase (decrease) associated with funds that are not available for withdrawal or use (such as funds held in escrow) and are associated with underlying transactions that are classified as investing activities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3213-108585

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

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-Name Accounting Standards Codification

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 15, 16, 17

-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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