Treasury Stock - Additional Information (Detail) - USD ($)	3 Months Ended					6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity, Class of Treasury Stock [Line Items]
Treasury stock, shares repurchased value	$ 11,128,000	$ 50,747,000	$ 24,475,000		$ 48,244,000
Treasury stock, shares	8,252,000		7,807,000			8,252,000
Treasury stock, cost	$ 720,755,000		$ 658,880,000			$ 720,755,000
Class A
Equity, Class of Treasury Stock [Line Items]
Treasury stock, shares repurchased	0	0	0		0
Treasury stock, shares repurchased value	$ 0	$ 0	$ 0		$ 0
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	90,136			0		444,769	362,148
Shares repurchased, average price per share	$ 123.45					$ 139.12	$ 133.21
Treasury stock, shares repurchased value	$ 11,100,000					$ 61,900,000	$ 48,200,000
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