Treasury Stock - Additional Information (Detail) - USD ($)		3 Months Ended						9 Months Ended
	Aug. 11, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Equity, Class of Treasury Stock [Line Items]
Treasury stock, shares repurchased value		$ 61,349,000	$ 11,128,000	$ 50,747,000	$ 24,475,000		$ 48,244,000
Treasury stock, shares		8,684,000			7,807,000			8,684,000
Treasury stock, cost		$ 782,104,000			$ 658,880,000			$ 782,104,000
Class A
Equity, Class of Treasury Stock [Line Items]
Treasury stock, shares repurchased		0	0	0	0		0
Treasury stock, shares repurchased value		$ 0	$ 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 repurchase program, authorized amount		$ 800,000,000.0						$ 800,000,000.0
Treasury stock, shares repurchased		0				0		444,769	362,148
Shares repurchased, average price per share								$ 139.12	$ 133.21
Treasury stock, shares repurchased value								$ 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
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
Treasury stock, shares repurchased value		$ 61,300,000						$ 61,300,000
Tender offer, purchase price maximum	$ 140.00
Tender offer, purchase price minimum	$ 122.00
Tender offer expiration date	Sep. 10, 2020
Expenses and fees related to tender offer		$ 800,000						$ 800,000
Class A | Tender Offer | Maximum
Equity, Class of Treasury Stock [Line Items]
Tender offer program, authorized amount	$ 250,000,000.0