Fair Value Accounting - Carrying And Estimated Fair Values Of Financial Instruments Carried On Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2020
Financial assets
Total investment securities available for sale	$ 10,918,329	$ 7,962,438
Loans held for sale	750,642	760,123
Mutual funds and mutual funds held in rabbi trusts	43,657	37,650
Loans, net of deferred fees and costs			$ 36,881,048
Derivative assets	191,708	401,295
Financial Liabilities
Non-interest-bearing deposits	16,392,653	13,477,854
Time deposits	4,117,475
Total deposits	49,427,276	46,691,571
Securities sold under repurchase agreements	264,133	227,922
Long-term debt	1,204,229	1,202,494
Fair Value, Measurements, Recurring
Financial assets
Trading securities	8,391	10,880
Total investment securities available for sale	10,918,329	7,962,438
Other investments	12,185	1,021
Mutual funds and mutual funds held in rabbi trusts	43,657	37,650
GGL/SBA loans servicing asset	3,233	3,258
Derivative assets	191,708	401,295
Financial Liabilities
Trading liability for short positions	200	7,717
Earnout liability	0	5,677
Mutual fund held in rabbi trusts	27,205	20,752
Derivative liabilities	98,602	157,167
Level 1 | Fair Value, Measurements, Recurring
Financial assets
Total cash, cash equivalents, and restricted cash	3,009,853	4,252,917
Trading securities	0	0
Total investment securities available for sale	117,838	20,257
Loans held for sale	0	0
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	43,657	37,650
Loans, net of deferred fees and costs	0	0
GGL/SBA loans servicing asset	0	0
FRB and FHLB stock	0	0
Derivative assets	0	0
Financial Liabilities
Non-interest-bearing deposits	0	0
Non-time interest-bearing deposits	0	0
Time deposits	0	0
Total deposits	0	0
Securities sold under repurchase agreements	264,133	227,922
Trading liability for short positions	0	0
Long-term debt	0	0
Earnout liability	0	0
Mutual fund held in rabbi trusts	27,205	20,752
Derivative liabilities	0	0
Level 2 | Fair Value, Measurements, Recurring
Financial assets
Total cash, cash equivalents, and restricted cash	0	0
Trading securities	8,391	10,880
Total investment securities available for sale	10,800,491	7,940,160
Loans held for sale	108,198	216,647
Other investments	0	0
Mutual funds and mutual funds held in rabbi trusts	0	0
Loans, net of deferred fees and costs	0	0
GGL/SBA loans servicing asset	0	0
FRB and FHLB stock	159,941	157,520
Derivative assets	191,708	401,295
Financial Liabilities
Non-interest-bearing deposits	16,392,653	13,477,854
Non-time interest-bearing deposits	28,917,148	27,265,521
Time deposits	4,125,673	5,970,146
Total deposits	49,435,474	46,713,521
Securities sold under repurchase agreements	0	0
Trading liability for short positions	200	7,717
Long-term debt	1,243,147	1,266,825
Earnout liability	0	0
Mutual fund held in rabbi trusts	0	0
Derivative liabilities	95,067	155,119
Level 3 | Fair Value, Measurements, Recurring
Financial assets
Total cash, cash equivalents, and restricted cash	0	0
Trading securities	0	0
Total investment securities available for sale	0	2,021
Loans held for sale	641,782	544,292
Other investments	12,185	1,021
Mutual funds and mutual funds held in rabbi trusts	0	0
Loans, net of deferred fees and costs	39,118,275	37,605,881
GGL/SBA loans servicing asset	3,233	3,258
FRB and FHLB stock	0	0
Derivative assets	0	0
Financial Liabilities
Non-interest-bearing deposits	0	0
Non-time interest-bearing deposits	0	0
Time deposits	0	0
Total deposits	0	0
Securities sold under repurchase agreements	0	0
Trading liability for short positions	0	0
Long-term debt	0	0
Earnout liability	0	5,677
Mutual fund held in rabbi trusts	0	0
Derivative liabilities	3,535	2,048
Carrying Value | Fair Value, Measurements, Recurring
Financial assets
Total cash, cash equivalents, and restricted cash	3,009,853	4,252,917
Trading securities	8,391	10,880
Total investment securities available for sale	10,918,329	7,962,438
Loans held for sale	750,642	760,123
Other investments	12,185	1,021
Mutual funds and mutual funds held in rabbi trusts	43,657	37,650
Loans, net of deferred fees and costs	38,884,361	37,647,248
GGL/SBA loans servicing asset	3,233	3,258
FRB and FHLB stock	159,941	157,520
Derivative assets	191,708	401,295
Financial Liabilities
Non-interest-bearing deposits	16,392,653	13,477,854
Non-time interest-bearing deposits	28,917,148	27,265,521
Time deposits	4,117,475	5,948,196
Total deposits	49,427,276	46,691,571
Securities sold under repurchase agreements	264,133	227,922
Trading liability for short positions	200	7,717
Long-term debt	1,204,229	1,202,494
Earnout liability		5,677
Mutual fund held in rabbi trusts	27,205	20,752
Derivative liabilities	98,602	157,167
Fair Value | Fair Value, Measurements, Recurring
Financial assets
Total cash, cash equivalents, and restricted cash	3,009,853	4,252,917
Trading securities	8,391	10,880
Total investment securities available for sale	10,918,329	7,962,438
Loans held for sale	749,980	760,939
Other investments	12,185	1,021
Mutual funds and mutual funds held in rabbi trusts	43,657	37,650
Loans, net of deferred fees and costs	39,118,275	37,605,881
GGL/SBA loans servicing asset	3,233	3,258
FRB and FHLB stock	159,941	157,520
Derivative assets	191,708	401,295
Financial Liabilities
Non-interest-bearing deposits	16,392,653	13,477,854
Non-time interest-bearing deposits	28,917,148	27,265,521
Time deposits	4,125,673	5,970,146
Total deposits	49,435,474	46,713,521
Securities sold under repurchase agreements	264,133	227,922
Trading liability for short positions	200	7,717
Long-term debt	1,243,147	1,266,825
Earnout liability		5,677
Mutual fund held in rabbi trusts	27,205	20,752
Derivative liabilities	$ 98,602	$ 157,167