The cumulative amount of the reporting entity's undistributed earnings or deficit.

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Name:	us-gaap_RetainedEarningsAccumulatedDeficit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

New Accounting Standards (Details) - USD ($) $ in Millions	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 1,846.7		$ 1,549.4
Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		$ 0.1