Employee Benefit Plans - Narrative (Details) $ in Millions	6 Months Ended
Jun. 30, 2020 USD ($)
SERPs
Defined Benefit Plan Disclosure [Line Items]
Contributions to benefit plan	$ 0.5
Estimated future contributions	0.7
Defined benefit plans
Defined Benefit Plan Disclosure [Line Items]
Contributions to benefit plan	4.8
Estimated future contributions	$ 27.0

Amount of contribution received by defined benefit plan from employer which increases plan assets.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
-Section 55
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration