Employee Benefits - Asset Held In Rabbi Trust By Plan Type (Details) - Primary Beneficiary - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Book Value	$ 75,002	$ 71,833
Mark-to-Market	19,003	19,850
Fair Value	94,005	91,683
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Book Value	5,230	5,157
Fair Value	5,230	5,157
Equities
Defined Benefit Plan Disclosure [Line Items]
Book Value	61,662	59,235
Mark-to-Market	18,828	19,492
Fair Value	80,490	78,727
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Book Value	8,110	7,441
Mark-to-Market	175	358
Fair Value	$ 8,285	$ 7,799