Retirement Plans - Textual (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Maximum percent of participants' base compensation matched	6.00%
Employer total contribution amount	$ 2.4	$ 2.8
Defined Benefit Pension Plans \| Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate for pension plan expense	4.32%
Defined Benefit Pension Plans \| Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Liability related to SERP plan	$ 0.3

Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan.

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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.

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Amount of cost for defined contribution plan.

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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans, classified as current.

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