Commitments and Contingencies - Letters of Credit (Details) $ in Millions	Dec. 31, 2017 USD ($)
Standby letters of credit \| Building lease and other commitments
Loss Contingencies [Line Items]
Letter of credit outstanding	$ 1.4

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.

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