Earnings Per Common Share - Computations of Basic Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income available to common shareholders:
Net income	$ 480,081	$ 526,091	$ 1,436,083	$ 1,371,861
Less: Preferred stock dividends	(16,103)	(18,130)	(52,364)	(54,390)
Net income available to common equity	463,978	507,961	1,383,719	1,317,471
Less: Income attributable to unvested stock-based compensation awards	(2,568)	(2,598)	(7,591)	(6,774)
Net income available to common shareholders	$ 461,410	$ 505,363	$ 1,376,128	$ 1,310,697
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	133,703	143,556	136,156	146,177
Less: Unvested stock-based compensation awards	(738)	(734)	(745)	(753)
Weighted-average shares outstanding	132,965	142,822	135,411	145,424
Basic earnings per common share	$ 3.47	$ 3.54	$ 10.16	$ 9.01