Retirement Plans, Multiemployer Pension Plan and Defined Contribution Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Plans [Abstract]
Aggregate contributions to the plans	$ 22,392	$ 17,247	$ 18,213
Seafarers Pension Trust [Member]
Retirement Plans [Abstract]
Pension contributions	$ 671	896
Contribution percentage to defined contribution plan	100.00%
Maximum contribution limit	5.00%
CPF [Member]
Retirement Plans [Abstract]
Pension contributions	$ 736	$ 238
Contribution percentage to defined contribution plan		94.00%