Consolidated Statement of Changes in Stockholders' Equity - Unaudited - USD ($) $ in Thousands		Total	Cumulative Effect, Period Of Adoption, Adjustment	Common Stock	Common Stock and Additional Paid-In Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period Of Adoption, Adjustment	Treasury Stock	AOCI, Net of Tax
Beginning balance (in shares) at Dec. 31, 2019				145,625,385
Beginning balance at Dec. 31, 2019		$ 5,017,617			$ 1,826,512	$ 3,689,377		$ (479,864)	$ (18,408)
Beginning balance (ASU 2016-13) at Dec. 31, 2019	[1]		$ (97,967)				$ (97,967)
Increase (Decrease) in Stockholders' Equity
Net income		144,824				144,824
Other comprehensive income		25,289							25,289
Net activity of common stock pursuant to various stock compensation plans and agreements (in shares)				281,396
Net activity of common stock pursuant to various stock compensation plans and agreements		(337)			7,272			(7,609)
Repurchase of common stock pursuant to the Stock Repurchase Program (in shares)				(4,471,682)
Repurchase of common stock pursuant to the Stock Repurchase Program		(145,966)						(145,966)
Cash dividends on common stock		(40,475)				(40,475)
Ending balance (in shares) at Mar. 31, 2020				141,435,099
Ending balance at Mar. 31, 2020		4,902,985			1,833,784	3,695,759		(633,439)	6,881
Beginning balance (in shares) at Dec. 31, 2020				141,565,229
Beginning balance at Dec. 31, 2020		5,269,175			1,858,519	4,000,414		(634,083)	44,325
Increase (Decrease) in Stockholders' Equity
Net income		204,994				204,994
Other comprehensive income		(134,365)							(134,365)
Net activity of common stock pursuant to various stock compensation plans and agreements (in shares)				277,807
Net activity of common stock pursuant to various stock compensation plans and agreements		(7,401)			7,582			(14,983)
Cash dividends on common stock		(47,376)				(47,376)
Ending balance (in shares) at Mar. 31, 2021				141,843,036
Ending balance at Mar. 31, 2021		$ 5,285,027			$ 1,866,101	$ 4,158,032		$ (649,066)	$ (90,040)

[1] Represents the impact of the adoption of Accounting Standards Update (“ASU”) 2016-13, Financial Instruments — Credit Losses (Topic 326) on January 1, 2020.