Leases - Maturities Of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Remainder of 2019	$ 17,133
2020	66,333
2021	60,175
2022	57,208
2023	39,102
Thereafter	12,633
Total lease payments	252,584
Less: imputed interest	(34,983)
Total operating lease liabilities	217,601
Current operating lease liabilities	52,840	$ 0
Non-current operating lease liabilities	164,761	$ 0
Vessels
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Remainder of 2019	15,416
2020	59,942
2021	54,481
2022	52,105
2023	34,580
Thereafter	2,470
Total lease payments	218,994
Less: imputed interest	(28,272)
Total operating lease liabilities	190,722
Current operating lease liabilities	47,914
Non-current operating lease liabilities	142,808
Facilities and Equipment
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Remainder of 2019	1,717
2020	6,391
2021	5,694
2022	5,103
2023	4,522
Thereafter	10,163
Total lease payments	33,590
Less: imputed interest	(6,711)
Total operating lease liabilities	26,879
Current operating lease liabilities	4,926
Non-current operating lease liabilities	$ 21,953