Pension and Other Postretirement Benefit Plans Actuarial Assumptions Used to Determine the Actuarial Present Value of Projected Benefit Obligation and Net Periodic Pensions Costs (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Weighted average assumed discount rate	0.45%	1.05%
Expected long-term rate of return on plan assets	0.45%	1.05%
Weighted average rate of compensation increase	1.50%	1.80%