Stockholders' Equity - Schedule of Stock Repurchase Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stockholders Equity Note [Abstract]
Shares repurchased		180,929	67,649	180,929
Average price per share		$ 192.75	$ 167.19	$ 192.75
Value of shares repurchased (in millions)	$ 11,310	$ 34,874	$ 11,300	$ 34,900

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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