Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Jul. 26, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Schedule Of Stockholders Equity [Line Items]
Shares repurchased, value				$ 184,892	$ 194,729
Preferred stock, shares authorized		15,000,000		15,000,000		15,000,000
Preferred stock, par value		$ 0.01		$ 0.01		$ 0.01
Dividend declared per share of common stock		$ 0.41	$ 0.38	$ 1.99	$ 1.93
Subsequent Event [Member]
Schedule Of Stockholders Equity [Line Items]
Dividend declared per share of common stock	$ 0.41
Dividend payable date	Aug. 18, 2017
Dividend date of record	Aug. 07, 2017
Dividend declare date	Jul. 26, 2017
November, 2016 [Member]
Schedule Of Stockholders Equity [Line Items]
Share repurchase remaining authorization		$ 170,234		$ 170,234
Share repurchase authorization expiration date				Dec. 31, 2018
Series A Preferred Stock [Member]
Schedule Of Stockholders Equity [Line Items]
Preferred stock, shares outstanding		0		0		0
Series B Preferred Stock [Member]
Schedule Of Stockholders Equity [Line Items]
Preferred stock, shares outstanding		0		0		0
Executive Officers [Member] | Class A Common Stock [Member]
Schedule Of Stockholders Equity [Line Items]
Shares repurchased, value				$ 14,700	$ 4,900