Pension and Postretirement Benefits Other Than Pension Plans - Qualified Plan - Net Settlement Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment [Abstract]
Net settlement loss	$ 1,577	$ 1,004	$ 1,577	$ 1,004
Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment [Abstract]
Net settlement loss	$ 1,600	$ 1,000	$ 1,600	$ 1,000