Employee Benefit Plans - Additional Information (Details) - USD ($)	6 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Supplemental executive retirement plan	$ 15,466,000	$ 15,035,000
Employer contributions to benefit plans	0
Expected funding of the SERP in the current year	$ 0

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

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