Capital Stock (Share Repurchase Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended	21 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Capital Stock
Number of Shares (in shares)	2,872,548	3,238,615	10,088,378
Average Repurchase Price per Share (in dollars per share)	$ 84.77		$ 82.01
Amount (in thousands)	$ 243,498	$ 281,774	$ 827,000
Stock Repurchase Program, remaining amount			$ 223,000

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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