Earnings Per Share - Schedule of Calculation of Basic and Diluted Earnings Per 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
Earnings Per Common Share - Basic:
Net income	$ 99,850	$ 101,465	$ 301,579	$ 240,210
Less: Preferred stock dividends	3,599	3,599	8,146	8,146
Less: Dividends and undistributed earnings allocated to unvested restricted shares	874	908	2,806	2,341
Earnings allocated to common shareholders - basic	$ 95,377	$ 96,958	$ 290,627	$ 229,723
Weighted average common shares outstanding	51,984	55,571	53,160	55,047
Earnings per common share - basic (in usd per share)	$ 1.83	$ 1.74	$ 5.47	$ 4.17
Earnings Per Common Share - Diluted:
Earnings allocated to common shareholders - basic	$ 95,377	$ 96,958	$ 290,627	$ 229,723
Adjustment for undistributed earnings allocated to unvested restricted shares	(17)	(25)	(37)	(49)
Earnings allocated to common shareholders - diluted	$ 95,360	$ 96,933	$ 290,590	$ 229,674
Weighted average common shares outstanding	51,984	55,571	53,160	55,047
Dilutive potential common shares	308	374	333	360
Weighted average common shares outstanding - diluted	52,292	55,945	53,493	55,407
Earnings per common share - diluted (in usd per share)	$ 1.82	$ 1.73	$ 5.43	$ 4.14