Business Segments - Operating Results and Other Key Financial Measures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Segment Reporting Information
Net interest income before provision for credit losses	$ 551,809	$ 395,706	$ 1,440,374	$ 1,125,874
Provision for (reversal of) credit losses	27,000	(10,000)	48,500	(25,000)
Noninterest income (loss)	75,552	73,109	233,739	214,406
Noninterest expense	215,973	205,384	602,283	585,984
Segment income (loss) before income taxes	384,388	273,431	1,023,330	779,296
Segment net income (loss)	295,339	225,449	791,320	655,185
Segment assets	62,576,061	60,959,110	62,576,061	60,959,110	$ 60,870,701
Consumer and Business Banking
Segment Reporting Information
Net interest income before provision for credit losses	326,411	176,678	823,998	500,352
Provision for (reversal of) credit losses	8,974	1,293	14,976	(598)
Noninterest income (loss)	30,819	22,099	84,402	69,873
Noninterest expense	104,005	90,575	294,395	267,511
Segment income (loss) before income taxes	244,251	106,909	599,029	303,312
Segment net income (loss)	173,982	76,577	426,695	217,257
Segment assets	17,002,000	14,687,023	17,002,000	14,687,023
Commercial Banking
Segment Reporting Information
Net interest income before provision for credit losses	222,996	189,791	662,037	559,579
Provision for (reversal of) credit losses	18,026	(11,293)	33,524	(24,402)
Noninterest income (loss)	48,641	43,272	145,750	123,342
Noninterest expense	81,386	66,731	235,804	204,042
Segment income (loss) before income taxes	172,225	177,625	538,459	503,281
Segment net income (loss)	122,869	126,984	384,237	360,275
Segment assets	32,836,381	27,861,690	32,836,381	27,861,690
Other
Segment Reporting Information
Net interest income before provision for credit losses	2,402	29,237	(45,661)	65,943
Provision for (reversal of) credit losses	0	0	0	0
Noninterest income (loss)	(3,908)	7,738	3,587	21,191
Noninterest expense	30,582	48,078	72,084	114,431
Segment income (loss) before income taxes	(32,088)	(11,103)	(114,158)	(27,297)
Segment net income (loss)	(1,512)	21,888	(19,612)	77,653
Segment assets	$ 12,737,680	$ 18,410,397	$ 12,737,680	$ 18,410,397