Commitments and Contingent Liabilities - Other (Details) $ in Millions	Dec. 31, 2018 USD ($)
Commitments and Contingent Liabilities
Letters of credit outstanding	$ 41.4
Surety bonds posted	$ 29.2

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration