Consolidated Statements of Changes in Shareholders' Equity - USD ($)	Total	Preferred Stock	Common Stock	Capital Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2020	$ 2,972,656,000	$ 0	$ 165,367,000	$ 1,875,626,000	$ 783,892,000	$ 147,771,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	277,538,000				277,538,000
Other comprehensive income (loss)	(150,146,000)					(150,146,000)
Cash dividends:
Dividends - common stock	(92,829,000)				(92,829,000)
Common stock issued	583,000		35,000	548,000
Common stock repurchased	(3,731,000)		(208,000)	(3,523,000)
Share-based compensation expense	7,497,000			7,497,000
Stock activity under incentive compensation plans	450,000		644,000	397,000	(591,000)
Ending Balance at Dec. 31, 2021	3,012,018,000	0	165,838,000	1,880,545,000	968,010,000	(2,375,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	428,287,000				428,287,000
Other comprehensive income (loss)	(784,047,000)					(784,047,000)
First Midwest Bancorp, Inc. merger:
Issuance of common stock	2,446,312,000		129,365,000	2,316,947,000
Issuance of preferred stock, net of issuance costs	243,719,000	230,500,000		13,219,000
Cash dividends:
Dividends - common stock	(163,505,000)				(163,505,000)
Preferred ($70.00 per share)	(14,118,000)				(14,118,000)
Common stock issued	809,000		52,000	757,000
Common stock repurchased	(71,182,000)		(3,960,000)	(67,222,000)
Share-based compensation expense	28,656,000			28,656,000
Stock activity under incentive compensation plans	1,646,000		1,608,000	1,363,000	(1,325,000)
Ending Balance at Dec. 31, 2022	5,128,595,000	230,500,000	292,903,000	4,174,265,000	1,217,349,000	(786,422,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	581,992,000				581,992,000
Other comprehensive income (loss)	47,613,000					47,613,000
First Midwest Bancorp, Inc. merger:
Issuance of common stock			129,365,000
Cash dividends:
Dividends - common stock	(163,895,000)				(163,895,000)
Preferred ($70.00 per share)	(16,135,000)				(16,135,000)
Common stock issued	1,076,000		75,000	1,001,000
Common stock repurchased	(44,308,000)		(2,640,000)	(41,668,000)
Share-based compensation expense	27,910,000			27,910,000
Stock activity under incentive compensation plans	52,000		2,317,000	(1,584,000)	(681,000)
Ending Balance at Dec. 31, 2023	$ 5,562,900,000	$ 230,500,000	$ 292,655,000	$ 4,159,924,000	$ 1,618,630,000	$ (738,809,000)