Defined Severance Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Retirement Benefits [Abstract]
Current service costs	$ 38,967	$ 30,555
Interest expense	1,704	594
Amortization of:
Prior service credit	906	23
Net actuarial loss	2,905	1,100
Net periodic benefit costs charged to expense	$ 44,482	$ 32,272