Retirement Plans, Multiemployer Pension Plan and Defined Contribution Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Plans [Abstract]
Aggregate contributions to the plans	$ 25,514,000	$ 25,409,000	$ 22,392,000
Seafarers Pension Trust [Member]
Retirement Plans [Abstract]
Pension contributions	617,000	$ 665,000
Contribution percentage to defined contribution plan		100.00%
Maximum contribution limit		5.00%
CPF [Member]
Retirement Plans [Abstract]
Pension contributions	$ 691,000	$ 693,000
Contribution percentage to defined contribution plan		98.00%