Employee Benefit Plans (Actual & Target Allocation of Fair Value by Asset Class) (Details) - UNITED STATES	Dec. 31, 2020	Dec. 31, 2019
Pension Benefits
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Actual	100.00%	100.00%
Pension Benefits | Fixed Maturity Securities
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Target	85.00%
Actual	85.00%	81.00%
Pension Benefits | Equity securities
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Target	11.00%
Actual	8.00%	12.00%
Pension Benefits | Alternative Securities
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Target	4.00%
Actual	7.00%	7.00%
Other Postretirement Benefits
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Actual	100.00%	100.00%
Other Postretirement Benefits | Fixed Maturity Securities
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Target	95.00%
Actual	95.00%	95.00%
Other Postretirement Benefits | Equity securities
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Target	5.00%
Actual	5.00%	5.00%
Other Postretirement Benefits | Alternative Securities
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Target	0.00%
Actual	0.00%	0.00%