Earnings Per Common Share - Computations of Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net income available to common equity	$ 478,410	$ 355,086	$ 1,349,628	$ 830,834
Less: Income attributable to unvested stock-based compensation awards	(2,449)	(1,686)	(6,816)	(3,630)
Net income available to common shareholders	$ 475,961	$ 353,400	$ 1,342,812	$ 827,204
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards	129,580	129,061	129,529	129,518
Less: Unvested stock-based compensation awards	(891)	(776)	(897)	(768)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock	155	70	154	63
Adjusted weighted-average shares outstanding	128,844	128,355	128,786	128,813
Diluted earnings per common share	$ 3.69	$ 2.75	$ 10.43	$ 6.42