Fair Value Measurements and Derivative Instruments - Recurring (Details) - USD ($) $ in Thousands			3 Months Ended
		Jul. 09, 2020	Sep. 30, 2020	Dec. 31, 2019
Liabilities:
Interest acquired		33.30%
Silversea Cruises
Liabilities:
Interest acquired		33.30%	33.30%
Fair Value, Measurements, Recurring | Level 1
Assets:
Derivative financial instruments	[1],[2]		$ 0	$ 0
Total Assets	[2]		0	0
Liabilities:
Derivative financial instruments	[2],[3]		0	0
Contingent consideration	[2],[4]		0	0
Total Liabilities	[2]		0	0
Fair Value, Measurements, Recurring | Level 2
Assets:
Derivative financial instruments	[1],[5]		46,367	39,994
Total Assets	[5]		46,367	39,994
Liabilities:
Derivative financial instruments	[3],[5]		363,955	257,728
Contingent consideration	[4],[5]		0	0
Total Liabilities	[5]		363,955	257,728
Fair Value, Measurements, Recurring | Level 3
Assets:
Derivative financial instruments	[1],[6]		0	0
Total Assets	[6]		0	0
Liabilities:
Derivative financial instruments	[3],[6]		0	0
Contingent consideration	[4],[6]		0	62,400
Total Liabilities	[6]		0	62,400
Total | Fair Value, Measurements, Recurring
Assets:
Derivative financial instruments	[1]		46,367	39,994
Total Assets			46,367	39,994
Liabilities:
Derivative financial instruments	[3]		363,955	257,728
Contingent consideration	[4]		0	62,400
Total Liabilities			$ 363,955	$ 320,128

[1] Consists of foreign currency forward contracts, interest rate swaps and fuel swaps. 

[2] Inputs based on quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access. Valuation of these items does not entail a significant amount of judgment.

[3] Consists of foreign currency forward contracts, interest rate swaps and fuel swaps.

[4] Any obligation under the contingent consideration related to the 2018 Silversea Cruises acquisition was eliminated during the quarter ended September 30 2020 as a result of our purchase of the remaining 33.3% non-controlling interest in Silversea Cruises. In prior periods, the contingent consideration was estimated by applying a Monte-Carlo simulation method using our closing stock price along with significant inputs not observable in the market, including the probability of achieving the milestones and estimated future operating results. The Monte-Carlo simulation is a generally accepted statistical technique used to generate a defined number of valuation paths in order to develop a reasonable estimate of fair value.

[5] Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. For foreign currency forward contracts, interest rate swaps and fuel swaps, fair value is derived using valuation models that utilize the income valuation approach. These valuation models take into account the contract terms, such as maturity, as well as other inputs, such as foreign exchange rates and curves, fuel types, fuel curves and interest rate yield curves. Derivative instrument fair values take into account the creditworthiness of the counterparty and the Company.

[6] Inputs that are unobservable.