Employee Benefit Plans - Qualified Pension Plan - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	$ 0	$ 0	$ 41,517

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Name:	us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant