Restructuring costs (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 3,992	$ 5,125
Current portion of restructuring reserve	1,572	1,513
Noncurrent portion of restructuring reserve	2,420
Workforce reductions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	237	353
Store closures [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 3,755	$ 4,772

Carrying amount as of the balance sheet date of known and estimated costs associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid after one year or beyond the next operating cycle, if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, and relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 420

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section P

-Paragraph Question 4

Name:	us-gaap_RestructuringReserveNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant