Amount of transactions with related party during the financial reporting period.

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Total cost of shares repurchased divided by the total number of shares repurchased.

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Number of shares that have been repurchased during the period and are being held in treasury.

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Related Party Transaction (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended			36 Months Ended
	May 10, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Related Party Transaction [Line Items]
Shares of common stock repurchased (in shares)		317,429	1,348,563	674,857	2,590,258
Richard A. Edlin
Related Party Transaction [Line Items]
Shares of common stock repurchased (in shares)	100,000
Block trade closing price (in USD per share)	$ 56.14
Richard A. Edlin \| Legal Services
Related Party Transaction [Line Items]
Transaction with related party			$ 0.2