Schedule of Common Stock Repurchases (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stockholders Equity Note [Abstract]
Shares repurchased	333,393	215,091	822,849
Cost of shares repurchased	$ 194,762	$ 144,422	$ 491,633
Average price per share repurchased	$ 584.18	$ 671.44	$ 597.48

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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