Earnings Per Share - Summary of Earnings Per Share, Basic and Diluted (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net income	$ 234,007	$ 196,247	$ 184,239	$ 188,817	$ 158,488	$ 147,060	$ 614,493	$ 494,365
Denominator for basic earnings per share (in shares)	81,836			83,719			82,811	84,170
Dilutive securities (in shares)	1,880			2,554			2,106	2,836
Denominator for diluted earnings per share (in shares)	83,716			86,273			84,917	87,006
Basic earnings per share (in dollars per share)	$ 2.86			$ 2.26			$ 7.42	$ 5.87
Diluted earnings per share (in dollars per share)	$ 2.80			$ 2.19			$ 7.24	$ 5.68