Postretirement Benefits Other than Pensions - General Information (Details) - Postretirement Health Coverage [Member] - age	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2001
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, funding status	us-gaap:UnfundedPlanMember
Minimum age of retirement under option one to avail benefit of post retirement	55 years
Minimum service period served at the time of retirement under option one to avail benefit of post retirement	15 years
Minimum age of retirement under option two to avail benefit of post retirement	65
Minimum service period served at time of retirement under option two to avail benefit of post retirement	10 years
Minimum for age plus years of service of retirement under amended plan to avail benefit of post retirement		60
Minimum service period served at the time of retirement under amended plan to avail benefit of post retirement		10 years