Fair Value Measurements and Derivative Instruments - Derivative Instruments, Interest Rate Risk, Foreign Currency Exchange Rate Risk (Narrative) (Details) $ in Thousands, € in Millions	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2017 EUR (€)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Fair Value Disclosures [Abstract]
Credit risk exposure on derivative instruments			$ 23,700
Gains and losses from derivatives involved in hedging relationships
Maximum length of time hedged in derivative contract			3 years	3 years
Interest rate swaps
Gains and losses from derivatives involved in hedging relationships
Notional amount	$ 3,900,000		$ 3,900,000			$ 4,000,000
Forward Contracts
Gains and losses from derivatives involved in hedging relationships
Change in fair value of foreign currency forward contracts recognized in earnings	21,300	$ (24,700)	35,100		$ (9,300)
Forward Contracts | Not Designated
Gains and losses from derivatives involved in hedging relationships
Notional amount	670,600		670,600
Foreign exchange contracts
Gains and losses from derivatives involved in hedging relationships
Notional amount	2,700,000		2,700,000			$ 1,300,000
Cruise ships on order
Gains and losses from derivatives involved in hedging relationships
Aggregate cost of ships on order, not including TUI cruises on order			12,600,000
Amount deposited for cost of ships on order	$ 322,400		$ 322,400
Percentage of aggregate cost exposed to fluctuations in the euro exchange rate	63.30%		63.30%			66.70%
Foreign currency debt
Gains and losses from derivatives involved in hedging relationships
Carrying Value of Non-derivative instrument Designated as hedging instrument			$ 353,493			$ 311,225
Foreign currency debt | TUI Cruises
Gains and losses from derivatives involved in hedging relationships
Carrying Value of Non-derivative instrument Designated as hedging instrument			$ 353,500	€ 310.0