Commitments and Contingent Liabilities - Narrative (Details) $ in Millions	6 Months Ended
Jun. 30, 2017 USD ($) Jurisdiction
Commitments And Contingent Liabilities [Line Items]
Number of jurisdiction \| Jurisdiction	30
Letter of Credit [Member]
Commitments And Contingent Liabilities [Line Items]
Letter of credit, outstanding \| $	$ 380.1

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