Commitments and Contingencies, Guarantees and Indemnifications (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Guarantees [Abstract]
Assets held as collateral	$ 0	$ 0
Payment or Performance Guarantee
Guarantees [Abstract]
Guarantees issued and outstanding	54,800,000	69,500,000
Current exposure under these guarantees	17,900,000	17,900,000
Payment or Performance Guarantee \| Surety Bonds
Guarantees [Abstract]
Guarantees issued and outstanding	$ 31,000,000	$ 29,600,000

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

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