Fair Value Measurements and Derivative Instruments (Recurring) (Details) - USD ($) $ in Thousands		12 Months Ended
	Jul. 09, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liabilities:
Contingent consideration expense		$ (45,126)	$ 18,400	$ 0
Interest acquired	33.30%
Silversea Cruises
Liabilities:
Interest acquired	33.30%	33.30%
Fair Value, Measurements, Recurring | Total Fair Value
Assets:
Derivative financial instruments		$ 108,539	39,994
Total Assets		108,539	39,994
Liabilities:
Derivative financial instruments		259,705	257,728
Contingent consideration		0	62,400
Total Liabilities		259,705	320,128
Fair Value, Measurements, Recurring | Level 1
Assets:
Derivative financial instruments		0	0
Total Assets		0	0
Liabilities:
Derivative financial instruments		0	0
Contingent consideration		0	0
Total Liabilities		0	0
Fair Value, Measurements, Recurring | Level 2
Assets:
Derivative financial instruments		108,539	39,994
Total Assets		108,539	39,994
Liabilities:
Derivative financial instruments		259,705	257,728
Contingent consideration		0	0
Total Liabilities		259,705	257,728
Fair Value, Measurements, Recurring | Level 3
Assets:
Derivative financial instruments		0	0
Total Assets		0	0
Liabilities:
Derivative financial instruments		0	0
Contingent consideration		0	62,400
Total Liabilities		$ 0	$ 62,400