Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash Flows From Operating Activities
Net income	$ 10,917	$ 625
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,045	3,763
Amortization of National Geographic fee	727	727
Amortization of deferred financing costs and other, net	608	552
Stock-based compensation	866	4,202
Deferred income taxes	347	(2,073)
Loss (gain) on foreign currency	451	(246)
Changes in operating assets and liabilities
Marine operating supplies and inventories	(400)	116
Prepaid expenses and other current assets	(1,754)	(1,358)
Unearned passenger revenues	(939)	4,261
Write-off of unamortized issuance costs related to debt refinancing	359
Other long-term assets	10	29
Other long-term liabilities	8
Accounts payable and accrued expenses	(5,727)	(7,861)
Net cash provided by operating activities	10,518	2,737
Cash Flows From Investing Activities
Purchases of property and equipment	(14,502)	(22,844)
Transfer to restricted cash and marketable securities	(13,180)	(4,411)
Net cash used in investing activities	(27,682)	(27,255)
Cash Flows From Financing Activities
Proceeds from long-term debt	200,000
Repayments of long-term debt	(170,625)	(438)
Payment of deferred financing costs	(6,297)
Repurchase under stock-based compensation plans and related tax impacts	(4,179)	(1,103)
Repurchase of warrants and common stock	(854)	(5,572)
Net cash provided by (used in) financing activities	18,045	(7,113)
Effect of exchange rate changes on cash	(40)	(3)
Net increase (decrease) in cash and cash equivalents	841	(31,634)
Cash and cash equivalents at beginning of period	96,443	135,416
Cash and cash equivalents at end of period	97,284	103,782
Cash paid during the period:
Interest	3,012	2,601
Income taxes	45	12
Non-cash investing and financing activities:
Additional paid-in capital exercise proceeds of option shares	1,682	168
Additional paid-in capital exchange proceeds used for option shares	$ (1,682)	$ (168)