Computation of Basic and Diluted Earnings (Loss) Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income available to common shareholders	$ 362,215	$ 389,589	$ 441,580
Less: Dividends paid on and earnings allocated to participating securities	(4,333)	(4,871)	(3,554)
Earnings applicable to common stock	$ 357,882	$ 384,718	$ 438,026
Weighted average common shares outstanding	465,380,010	487,287,872	487,073,951
Basic earnings per common share	$ 0.77	$ 0.79	$ 0.90
Potential dilutive common shares	283,322
Total shares for diluted earnings per common share computation	465,663,332	487,287,872	487,073,951
Diluted earnings per common share and common share equivalents	$ 0.77	$ 0.79	$ 0.90