Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gross amount of port costs included in passenger ticket revenues	$ 569.5	$ 570.3	$ 561.1
Exchange gains (losses) recorded in other income (expense)	(75.6)	39.8	34.6
Exposure under foreign currency forward contracts, foreign currency collar options, fuel call options, interest rate and fuel swap agreements	$ 212.8
Ships
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life	30 years
Projected residual value	15.00%
Ships | Lower Limit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Drydock services period	30 months
Ships | Upper Limit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Drydock services period	60 months
Media advertising
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Advertising costs	$ 233.5	240.3	242.8
Brochure, production and direct mail costs
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Advertising costs	$ 126.7	120.8	$ 127.1
Marketing, Selling and Administrative Expenses
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restructuring charges		$ 8.5