Employee Benefit Plans (Actual & Target Allocation of Fair Value by Asset Class) (Details) - U.S. Plans	Dec. 31, 2017	Dec. 31, 2016
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	82.00%
Actual	82.00%	81.00%
Pension Benefits | Equity securities
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Target	10.00%
Actual	10.00%	11.00%
Pension Benefits | Alternative Securities
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Target	8.00%
Actual	8.00%	8.00%
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	85.00%
Actual	84.00%	76.00%
Other Postretirement Benefits | Equity securities
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Target	15.00%
Actual	15.00%	24.00%
Other Postretirement Benefits | Alternative Securities
Actual weighted average asset allocation by major asset class for the Invested Plans [Abstract]
Target	0.00%
Actual	1.00%	0.00%