Fair Value Measurements (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Other Asset Impairment Charges		$ 204.0	$ 495.4
Property, Plant, and Equipment, Fair Value Disclosure	[1]	$ 464.7	$ 342.5	[2]

[1] Measured as of the impairment date using the income approach and a 10.8% risk-adjusted rate of interest, resulting in a Level 3 fair value measurement.

[2] Includes $104.0 million fair value of vessels determined using the transaction price of a similar vessel, resulting in a Level 2 fair value measurement.