Leases - Maturities Of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Less than one year	$ 60,649	$ 66,820
One to two years	57,541	60,452
Two to three years	39,229	57,363
Three to four years	6,844	39,202
Four to five years	2,340	6,819
Over five years	4,054	6,251
Total lease payments	170,657	236,907
Less: imputed interest	(18,049)	(31,295)
Total operating lease liabilities	152,608	205,612
Current operating lease liabilities	51,599	53,785
Non-current operating lease liabilities	101,009	151,827
Vessels
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Less than one year	54,621	60,210
One to two years	52,106	54,564
Two to three years	34,580	52,106
Three to four years	2,470	34,580
Four to five years	0	2,470
Over five years	0	0
Total lease payments	143,777	203,930
Less: imputed interest	(13,352)	(24,846)
Total operating lease liabilities	130,425	179,084
Current operating lease liabilities	46,748	48,716
Non-current operating lease liabilities	83,677	130,368
Facilities and Equipment
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Less than one year	6,028	6,610
One to two years	5,435	5,888
Two to three years	4,649	5,257
Three to four years	4,374	4,622
Four to five years	2,340	4,349
Over five years	4,054	6,251
Total lease payments	26,880	32,977
Less: imputed interest	(4,697)	(6,449)
Total operating lease liabilities	22,183	26,528
Current operating lease liabilities	4,851	5,069
Non-current operating lease liabilities	$ 17,332	$ 21,459