Treasury Stock - Additional Information (Detail) - USD ($)	3 Months Ended				9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Equity, Class of Treasury Stock [Line Items]
Treasury stock, shares repurchased value		$ 61,349,000	$ 11,128,000	$ 50,747,000
Treasury stock, shares	8,684,000				8,684,000		8,684,000
Treasury stock, cost	$ 782,104,000				$ 782,104,000		$ 782,104,000
Class A
Equity, Class of Treasury Stock [Line Items]
Treasury stock, shares repurchased		0	0	0
Treasury stock, shares repurchased value		$ 0	$ 0	$ 0
Class A | Tender Offer
Equity, Class of Treasury Stock [Line Items]
Treasury stock, shares repurchased		432,313				432,313
Shares repurchased, average price per share		$ 140.00				$ 140.00
Treasury stock, shares repurchased value		$ 61,300,000				$ 61,300,000
Expenses and fees related to tender offer		$ 800,000				$ 800,000
Tender offer expiration period		2020-09				2020-09
Class A | Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Shares repurchased program expiration date					Apr. 29, 2023
Stock authorized to repurchase by board of directors	$ 800,000,000.0				$ 800,000,000.0
Treasury stock, shares repurchased	0	0			0	444,769
Shares repurchased, average price per share						$ 139.12
Treasury stock, shares repurchased value						$ 61,900,000
Treasury stock, shares	5,674,226				5,674,226
Shares repurchased, average price per share	$ 104.13				$ 104.13
Treasury stock, cost	$ 590,900,000				$ 590,900,000
Stock remaining available for repurchase	$ 209,100,000				$ 209,100,000