Employee Benefit Plans - Profit Sharing Plan (Details) - Multiple employer 401(k) profit sharing plan $ in Millions	3 Months Ended
Dec. 31, 2017 USD ($) year	Dec. 31, 2016 USD ($)
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, requisite service period	1 year
Defined contribution plan, minimum age requirement \| year	21
Contributions by the Company \| $	$ 1.8	$ 1.5

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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