Recent Authoritative Accounting Guidance (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total stockholders’ equity	$ 1,933.4	$ 1,959.8	$ 1,956.1	$ 2,013.9
Off-Balance Sheet, Credit Loss, Liability	3.4	3.7	2.1	0.0
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total stockholders’ equity	$ 988.2	$ 962.1	$ 897.6	$ 953.6