Long-Term Debt (Details) In Millions, unless otherwise specified		1 Months Ended			6 Months Ended
	Jun. 30, 2013 Credit agreement USD ($)	Mar. 31, 2013 Revolving credit facility due July 2016 USD ($)	Jul. 31, 2013 Unsecured term loan Oasis-class ship third USD ($)	Jul. 31, 2013 Unsecured term loan Oasis-class ship third EUR (€)	Jun. 30, 2013 Unsecured Euro-denominated term loan facility USD ($)	Jun. 30, 2013 Unsecured Euro-denominated term loan facility EUR (€)
Long-Term Debt
Borrowing capacity	$ 1,700.0	$ 1,100.0	$ 1,200.0	€ 892.2
Increase in capacity		20.0
Floating rate base			EURIBOR	EURIBOR	EURIBOR	EURIBOR
Long-term debt					$ 474.5	€ 365.0
Margin on floating rate base (as a percent)			1.15%	1.15%	3.00%	3.00%
Percentage of unsecured term loan guaranteed			100.00%	100.00%
Unsecured term loan, amortization period			12 years	12 years
Interest rate on debt instrument (as a percent)			2.60%	2.60%