Fair Value Measurements and Derivative Instruments (Derivative Instruments) (Details)	12 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2013 Foreign currency forward Not Designated USD ($)	Dec. 31, 2012 Foreign currency forward Not Designated USD ($)	Dec. 31, 2011 Foreign currency forward Not Designated USD ($)	Dec. 31, 2013 Foreign exchange contracts USD ($)	Dec. 31, 2012 Foreign exchange contracts USD ($)	Dec. 31, 2013 Cash flow hedge Foreign currency forward EUR (€)	Dec. 31, 2013 €745 million unsecured senior notes, 5.63%, due 2014 EUR (€)	Dec. 31, 2012 €745 million unsecured senior notes, 5.63%, due 2014 EUR (€)
Gains and losses from derivatives involved in hedging relationships
Aggregate cost of ships on order	$ 4,700,000,000
Amount deposited for cost of ships on order	518,800,000
Percentage of aggregate cost exposed to fluctuations in the euro exchange rate	36.30%	49.70%
Amount of foreign currency forward contracts not designated as hedging instruments				406,700,000			2,500,000,000	1,200,000,000	365,000,000
Unsecured term loan										745,000,000	1,000,000,000.0
Interest rate on hedged debt (as a percent)										5.625%	5.625%
Change in fair value of foreign currency forward contracts recognized in earnings				(19,300,000)	7,700,000	(1,100,000)
Exchange gains (losses) recorded in other income (expense)	13,400,000	(11,800,000)	(1,600,000)	13,400,000	(11,800,000)	(1,600,000)
Gain (loss) on foreign currency derivatives recorded in earnings, net						$ (2,700,000)