Leases - Maturities Of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Less than one year	$ 61,548	$ 60,649
One to two years	47,991	57,541
Two to three years	12,702	39,229
Three to four years	3,212	6,844
Four to five years	1,048	2,340
Over five years	4,443	4,054
Total lease payments	130,944	170,657
Less: imputed interest	(11,470)	(18,049)
Total operating lease liabilities	119,474	152,608
Current operating lease liabilities	55,051	51,599
Non-current operating lease liabilities	64,423	101,009
Vessels
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Less than one year	55,817	54,621
One to two years	43,045	52,106
Two to three years	8,013	34,580
Three to four years		2,470
Total lease payments	106,875	143,777
Less: imputed interest	(7,388)	(13,352)
Total operating lease liabilities	99,487	130,425
Current operating lease liabilities	50,295	46,748
Non-current operating lease liabilities	49,192	83,677
Facilities and Equipment
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Less than one year	5,731	6,028
One to two years	4,946	5,435
Two to three years	4,689	4,649
Three to four years	3,212	4,374
Four to five years	1,048	2,340
Over five years	4,443	4,054
Total lease payments	24,069	26,880
Less: imputed interest	(4,082)	(4,697)
Total operating lease liabilities	19,987	22,183
Current operating lease liabilities	4,756	4,851
Non-current operating lease liabilities	$ 15,231	$ 17,332