Leases Leases - Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($)
Operating Leased Assets [Line Items]
Sale leasback transaction, deferred gain, gross	$ 5.0
Sale-leaseback of Trailers to an Unaffiliated Third Party
Operating Leased Assets [Line Items]
Sale leaseback transaction, sale price of investing activities	$ 43.8

Amount of cash inflow after closing and debt issuance costs received by a seller-lessee in a sale-leaseback recognized in investing activities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 55
-Paragraph 51
-URI http://asc.fasb.org/extlink&oid=82846721&loc=d3e51840-112757

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 55
-Paragraph 50
-URI http://asc.fasb.org/extlink&oid=82846721&loc=d3e51831-112757

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=82846721&loc=d3e51843-112757

Name:	us-gaap_SaleLeasebackTransactionNetProceedsInvestingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration