Guarantees (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Guarantees [Abstract]
Letters of credit	$ 234,482	$ 210,995
Surety bonds	$ 99,831r_SuretyBondOutstanding	$ 99,486r_SuretyBondOutstanding

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

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