Supplemental Cash Flow and Noncash Investing Transactions (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) tankContainer	Dec. 31, 2020 USD ($) tankContainer	Dec. 31, 2019 USD ($) tankContainer
Noncash or Part Noncash Divestitures [Line Items]
Number of railcars received | tankContainer	2,329	732	157
Assets Held-for-sale, Long Lived, Fair Value Disclosure	$ 3.8	$ 4.8
Supplemental Cash Flow Information
Interest Paid, Excluding Capitalized Interest, Operating Activities	196.6	189.8	$ 185.1
Income taxes paid (refunded), net	10.3	21.4	11.6
Portfolio proceeds	$ 187.1	$ 131.1	$ 250.3