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Shareholders' Equity - Share repurchase program (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Treasury stock, value of shares acquired	$ 83,472	$ 2,871	$ 282,762
Treasury stock, shares acquired (shares)	2,850,102	110,598	10,559,850
Treasury stock, average cost per share	$ 29.29	$ 25.96	$ 26.78
Common shares held in treasury (shares)	172,280,199	168,997,994	168,282,449
Common shares held in treasury, at cost	$ 2,500,000
Common shares
Class of Stock [Line Items]
Remaining share repurchase authorization	$ 916,500
Cumulative number of shares acquired since inception of share repurchase program	389,200,000
Aggregate purchase price of shares acquired since inception of share repurchase program	$ 4,100,000

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Cumulative number of shares that have been repurchased since the inception of the share repurchase program.

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Aggregate cumulative purchase price of common and preferred stock that have been repurchased since the inception of the share repurchase program.

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Amount remaining of a stock repurchase plan authorized.

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

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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