Long-term obligations (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended	1 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2014 Subsequent Event [Member]
Debt Instrument [Line Items]
Amortization	$ 0.7	$ 0.8	$ 0.6
Sale Leaseback Transaction, Amount Due under Financing Arrangement				$ 0.9
Sale Leaseback Transaction, Lease Terms				three year sale leaseback transaction
Sale Leaseback Transaction, Imputed Interest Rate				3.00%

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=31042434&loc=d3e3602-108585

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- Details

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- Definition

The liability due as of the balance sheet date for leasebacks accounted for using the deposit method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6452660&loc=d3e36991-112694

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 40

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6456341&loc=d3e50796-112755

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- Definition

The financing cost related to leases that have been recorded under the deposit method, as a financing or as a capital leases in connection with the transaction involving the sale of property to another party and the lease of the property back to the seller.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Imputed Interest Rate

-URI http://asc.fasb.org/extlink&oid=6515215

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- Definition

A description of the terms of the lease(s) related to the assets being leased-back in connection with the transaction involving the sale of property to another party and the lease of the property back to the seller.

+ References

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