Amount of cumulative tax effect on beginning retained earnings from change in accounting principle.

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

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Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2014	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		$ 1,406.5	$ 1,274.7
Revenue practical expedient
Practical expedient, incremental costs of obtaining a contract		true
ASC 606 \| Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 6.1
income tax effects on retained earrings	$ 2.1