Fair Value Measurements and Derivative Instruments (Nonfinancial Instruments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Silversea goodwill, impairment	$ 576,208
Right-of-use assets, impairment	65,900
Total, impairment	1,566,380	$ 0	$ 33,651
Indefinite-life intangible assets, net carrying value	321,475	$ 352,275
Silversea Cruises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Silversea goodwill, impairment	576,208
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Indefinite-life intangible asset, impairment	30,800
Long-lived assets, impairment	727,063
Right-of-use assets, impairment	65,909
Equity method investments, impairment	39,735
Total, impairment	1,439,715
Fair Value, Measurements, Nonrecurring | Silversea Cruises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Silversea goodwill, impairment	576,208
Fair Value, Measurements, Nonrecurring | Total Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Indefinite-life intangible asset	318,700
Long-lived assets	577,193
Right-of-use assets	67,265
Equity method investments	0
Total	1,471,736
Fair Value, Measurements, Nonrecurring | Total Carrying Amount | Silversea Cruises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Silversea Goodwill	508,578
Fair Value, Measurements, Nonrecurring | Total Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Indefinite-life intangible asset	318,700
Long-lived assets	577,193
Right-of-use assets	67,265
Equity method investments	0
Total	1,471,736
Fair Value, Measurements, Nonrecurring | Total Fair Value | Silversea Cruises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Silversea Goodwill	508,578
Fair Value, Measurements, Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Indefinite-life intangible asset	318,700
Long-lived assets	577,193
Right-of-use assets	67,265
Equity method investments	0
Total	$ 1,471,736
Fair Value, Measurements, Nonrecurring | Level 3 | Discount rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Indefinite-lived intangible assets, measurement input	13.25%
Fair Value, Measurements, Nonrecurring | Level 3 | Royalty fee percentage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Indefinite-lived intangible assets, measurement input	3.00%
Fair Value, Measurements, Nonrecurring | Level 3 | Silversea Cruises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Silversea Goodwill	$ 508,578
Fair Value, Measurements, Nonrecurring | Level 3 | Silversea Cruises | Weighted average cost of capital
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, measurement input	12.75%