Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Ships	$ 23,714,745	$ 23,978,822
Ship improvements	2,410,525	2,359,639
Ships under construction	642,235	354,425
Land, buildings and improvements, including leasehold improvements and port facilities	250,079	341,605
Computer hardware and software, transportation equipment and other	762,512	1,108,301
Total property and equipment	27,780,096	28,142,792
Less-accumulated depreciation and amortization	(8,044,916)	(7,981,365)
Property and equipment, net	$ 19,735,180	$ 20,161,427