Long-Term Debt (Details)	3 Months Ended		9 Months Ended			1 Months Ended		1 Months Ended		9 Months Ended	1 Months Ended	9 Months Ended	1 Months Ended		1 Months Ended	9 Months Ended		3 Months Ended
	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2013 Credit agreement USD ($)	Mar. 31, 2013 Revolving credit facility due July 2016 USD ($)	Aug. 31, 2013 Revolving credit facility due November 2014 USD ($)	Aug. 31, 2013 Revolving credit facility due August 2018 USD ($)	Aug. 31, 2013 Revolving credit facility due August 2018 LIBOR	Sep. 30, 2013 Revolving credit facility due August 2018 LIBOR	Aug. 31, 2013 Unsecured term loan LIBOR USD ($)	Sep. 30, 2013 Unsecured term loan LIBOR	Jul. 31, 2013 Unsecured term loan Oasis-class ship third EUR (€)	Sep. 30, 2013 Unsecured term loan Oasis-class ship third USD ($)	Jul. 31, 2013 Unsecured term loan Oasis-class ship third EURIBOR	Sep. 30, 2013 Unsecured Euro-denominated term loan facility USD ($)	Jun. 30, 2013 Unsecured Euro-denominated term loan facility EUR (€)	Sep. 30, 2013 Unsecured senior notes due 2015 USD ($)
Long-Term Debt
Long-term debt																$ 494,100,000	€ 365,000,000
Floating rate base									LIBOR		LIBOR				EURIBOR	EURIBOR
Margin on floating rate base (as a percent)										1.75%		2.12%			1.15%	3.00%
Borrowing capacity					2,000,000,000	1,100,000,000	525,000,000	850,000,000					892,200,000	1,200,000,000
Percentage of unsecured term loan guaranteed													100.00%
Unsecured term loan, amortization period													12 years
Interest rate on debt instrument (as a percent)													2.60%					11.875%
Maximum borrowing capacity under credit agreement											380,000,000
Commitment fee on undrawn amount (as a percent)											0.37%
Facility fee (as a percent)										0.37%
Increase in capacity						20,000,000		300,000,000
Outstanding amount of debt repurchased																		21,000,000
Premium, fees and related cost of repurchase of unsecured debt																		24,900,000
Loss on early extinguishment of debt	$ 4,206,000	$ 7,485,000	$ 4,206,000	$ 7,485,000														$ 4,200,000