Consolidated Statements of Changes in Shareholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Capital Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period at Dec. 31, 2021	$ 3,012,018	$ 0	$ 165,838	$ 1,880,545	$ 968,010	$ (2,375)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(27,586)				(27,586)
Other comprehensive income (loss)	(335,824)					(335,824)
First Midwest Bancorp, Inc. merger:
Issuance of common stock	2,446,312		129,365	2,316,947
Issuance of preferred stock, net of issuance costs	243,719	230,500		13,219
Cash dividends:
Dividends - common stock	(40,782)				(40,782)
Preferred dividends	(2,017)				(2,017)
Common stock issued	165		10	155
Common stock repurchased	(70,078)		(3,890)	(66,188)
Share-based compensation expense	6,284			6,284
Stock activity under incentive compensation plans	(97)		1,636	(1,368)	(365)
Balance at end of period at Mar. 31, 2022	5,232,114	230,500	292,959	4,149,594	897,260	(338,199)
Balance at beginning of period at Dec. 31, 2021	3,012,018	0	165,838	1,880,545	968,010	(2,375)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	87,399
Other comprehensive income (loss)	(566,758)
First Midwest Bancorp, Inc. merger:
Issuance of common stock	2,446,312	243,870
Balance at end of period at Jun. 30, 2022	5,078,783	230,500	292,893	4,157,543	966,980	(569,133)
Balance at beginning of period at Mar. 31, 2022	5,232,114	230,500	292,959	4,149,594	897,260	(338,199)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	114,985				114,985
Other comprehensive income (loss)	(230,934)					(230,934)
Cash dividends:
Dividends - common stock	(40,901)				(40,901)
Preferred dividends	(4,033)				(4,033)
Common stock issued	162		10	152
Common stock repurchased	(322)		(21)	(301)
Share-based compensation expense	7,813			7,813
Stock activity under incentive compensation plans	(101)		(55)	285	(331)
Balance at end of period at Jun. 30, 2022	5,078,783	230,500	292,893	4,157,543	966,980	(569,133)
Balance at beginning of period at Dec. 31, 2022	5,128,595	230,500	292,903	4,174,265	1,217,349	(786,422)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	146,600				146,600
Other comprehensive income (loss)	78,064					78,064
Cash dividends:
Dividends - common stock	(41,088)				(41,088)
Preferred dividends	(4,034)				(4,034)
Common stock issued	262		15	247
Common stock repurchased	(43,710)		(2,598)	(41,112)
Share-based compensation expense	12,742			12,742
Stock activity under incentive compensation plans	(5)		1,602	(1,412)	(195)
Balance at end of period at Mar. 31, 2023	5,277,426	230,500	291,922	4,144,730	1,318,632	(708,358)
Balance at beginning of period at Dec. 31, 2022	5,128,595	230,500	292,903	4,174,265	1,217,349	(786,422)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	301,636
Other comprehensive income (loss)	(22,211)
First Midwest Bancorp, Inc. merger:
Issuance of common stock	0	0
Balance at end of period at Jun. 30, 2023	5,292,095	230,500	292,597	4,149,089	1,428,542	(808,633)
Balance at beginning of period at Mar. 31, 2023	5,277,426	230,500	291,922	4,144,730	1,318,632	(708,358)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	155,036				155,036
Other comprehensive income (loss)	(100,275)					(100,275)
Cash dividends:
Dividends - common stock	(40,932)				(40,932)
Preferred dividends	(4,033)				(4,033)
Common stock issued	272		20	252
Common stock repurchased	(105)		(8)	(97)
Share-based compensation expense	5,247			5,247
Stock activity under incentive compensation plans	(541)		663	(1,043)	(161)
Balance at end of period at Jun. 30, 2023	$ 5,292,095	$ 230,500	$ 292,597	$ 4,149,089	$ 1,428,542	$ (808,633)