Pension Plans - Qualified Plan - Allocation of Defined Benefit Pension Plans Assets (Details) - Pension Plan [Member] - Qualified Plan [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan assets	$ 66,000	$ 59,653	$ 69,245
Defined Benefit Plan, Cash [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan assets	43	162
Mutual Funds [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan assets	$ 65,957	$ 59,491