Earnings Per Common Share - Computations of Basic Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income available to common shareholders:
Net income	$ 1,929,149	$ 1,918,080	$ 1,408,306
Less: Preferred stock dividends	(69,441)	(72,521)	(72,734)
Net income available to common equity	1,859,708	1,845,559	1,335,572
Less: Income attributable to unvested stock-based compensation awards	(10,199)	(9,531)	(8,069)
Net income available to common shareholders	$ 1,849,509	$ 1,836,028	$ 1,327,503
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	135,169	144,740	153,092
Less: Unvested stock-based compensation awards	(741)	(748)	(933)
Weighted-average shares outstanding	134,428	143,992	152,159
Basic earnings per common share	$ 13.76	$ 12.75	$ 8.72