Operating Leases - Additional Information (Details) (Vehicles [Member], USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2014
Operating Leased Assets [Line Items]
Term of non-cancellable pick-up truck leases (in years)	1 year
Aggregate residual value guarantee	$ 56,002
Minimum [Member]
Operating Leased Assets [Line Items]
Average pick-up truck lease term (in months)	28 months
Maximum [Member]
Operating Leased Assets [Line Items]
Renewal options for non-cancellable pick-up truck leases, maximum (in months)	72 months
Average pick-up truck lease term (in months)	36 months

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