Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net income/(loss)	$ 248,009	$ 184,898	$ (35,063)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Depreciation	47,911	44,862	42,778
Amortization of deferred drydocking costs	13,244	8,656	7,379
Amortization of operating lease right-of-use assets	30,233	16,364	12,517
Amortization of debt discount and debt issuance costs	2,130	7,083	6,272
Loss on debt extinguishment	4,169	6,085	0
(Gain)/loss on sale of vessels	(9,308)	(3,966)	490
Impairment of operating lease right-of-use assets	2,212	0	352
Unrealized loss/(gain) on derivative instruments, net	1,933	68	(537)
Stock-based compensation expense	6,108	3,481	3,048
Drydocking expenditures	(18,422)	(21,906)	(14,294)
Changes in operating assets and liabilities:
Accounts payable	(257)	10,067	(4,171)
Accounts receivable	(4,141)	(14,967)	1,918
Accrued interest	185	(1,733)	(631)
Inventories	(10,429)	(6,027)	4,199
Operating lease liabilities	(30,227)	(17,132)	(13,256)
Collateral on derivatives	14,172	(15,081)	0
Fair value of derivatives, other current and noncurrent assets	(105)	(1,622)	(229)
Other accrued liabilities	4,452	6,205	(3,007)
Prepaid expenses	(1,170)	(179)	1,449
Unearned charter hire revenue	(2,416)	4,015	3,380
Net cash provided by operating activities	298,283	209,171	12,595
Cash flows from investing activities:
Purchase of vessels and vessel improvements	(27,676)	(128,254)	(980)
Advances for vessel purchases	(3,638)	0	(3,250)
Purchase of scrubbers and ballast water treatment systems	(7,307)	(6,712)	(28,377)
Proceeds from hull and machinery insurance claims	286	354	3,944
Proceeds from sale of vessels	14,917	9,163	23,225
Purchase of other fixed assets	(274)	(33)	(54)
Net cash used in investing activities	(23,692)	(125,481)	(5,492)
Cash flows from financing activities:
Proceeds from issuance of shares under ATM Offering, net of commissions	0	27,138	0
Payments on Equity Offerings, net of issuance costs		(493)
Proceeds from Equity Offerings, net of issuance costs	201		23,498
Financing costs paid to lenders	(18)	(6,351)	(381)
Other financing costs	0	(731)	(142)
Dividends paid	(104,991)	(25,763)	0
Cash received from exercise of stock options	85	56	0
Cash used to settle fractional shares	0	0	(13)
Cash paid for taxes related to net share settlement of equity awards	(2,355)	(1,937)	(1,163)
Net cash (used in)/provided by financing activities	(171,059)	(86,317)	22,615
Net increase/(decrease) in cash, cash equivalents and restricted cash	103,532	(2,627)	29,718
Cash, cash equivalents and restricted cash at beginning of year	86,222	88,849	59,130
Cash, cash equivalents and restricted cash at end of year	189,754	86,222	88,849
New First Lien Facility
Cash flows from financing activities:
Repurchase of Convertible Bond Debt	(14,181)	0	0
Norwegian Bond Debt
Cash flows from financing activities:
Repayments of long-term debt	0	(184,356)	(8,000)
New Ultraco Debt Facility
Cash flows from financing activities:
Proceeds from debt	0	16,500	22,550
Repayments of long-term debt	0	(182,930)	(28,734)
New Ultraco Revolver Facility
Cash flows from financing activities:
Proceeds from debt	0	55,000	55,000
Repayments of long-term debt	0	(55,000)	(55,000)
Super Senior Revolver Facility
Cash flows from financing activities:
Proceeds from debt	0	0	15,000
Repayments of long-term debt	0	(15,000)	0
Holdco Revolving Credit Facility
Cash flows from financing activities:
Proceeds from debt	0	24,000	0
Repayments of long-term debt	0	(24,000)	0
Global Ultraco Debt Facility
Cash flows from financing activities:
Proceeds from debt	0	300,000	0
Repayments of long-term debt	(49,800)	(12,450)	0
Global Ultraco Revolver Loan
Cash flows from financing activities:
Proceeds from debt	0	50,000	0
Repayments of long-term debt	$ 0	$ (50,000)	$ 0