Operating Leases - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2014
Leases, Operating [Abstract]
Term of non-cancellable pick-up truck leases (in years)	1 year
Renewal options for non-cancellable pick-up truck leases, maximum (in months)	72 months
Average pick-up truck lease term, minimum (in months)	28 months
Average pick-up truck lease term, maximum (in months)	36 months
Aggregate residual value guarantee	$ 56,711
Loss on disposal reserve	$ 19

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