Fair Value Accounting (Carrying and Estimated Fair Values of Financial Instruments Carried on Balance Sheet) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financial assets
Trading securities		$ 7,212
Investment securities available for sale	$ 7,197,493	6,778,670
Loans receivable held-for-sale		115,173
Private equity investments		19,389
GGL/SBA loans servicing asset		3,040
Derivative assets		140,016
Financial liabilities
Non-interest-bearing deposits	12,555,714	9,439,485
Total deposits	44,194,580	38,405,504
Federal funds purchased and securities sold under repurchase agreements	225,576	165,690
Other short-term borrowings	300,000	1,753,560
Long-term debt	2,327,921	2,153,897
Earnout liability		11,016
Derivative liabilities		37,071
Level 1
Financial assets
Total cash, cash equivalents, restricted cash, and restricted cash equivalents	1,571,225	1,186,918
Trading securities	0	0
Investment securities available for sale	19,921	19,855
Loans receivable held-for-sale	0	0
Private equity investments	0	15,502
Mutual funds and mutual funds held in rabbi trusts	34,219	32,348
Loans, net	0	0
GGL/SBA loans servicing asset	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
Federal funds purchased and securities sold under repurchase agreements	225,576	165,690
Trading liability for short positions		1,560
Other short-term borrowings	0	0
Long-term debt	0	0
Earnout liability	0	0
Derivative liabilities	0	0
Level 2
Financial assets
Total cash, cash equivalents, restricted cash, and restricted cash equivalents	0	0
Trading securities	4,626	7,212
Investment securities available for sale	7,175,910	6,756,710
Loans receivable held-for-sale	266,306	115,173
Private equity investments	0	0
Mutual funds and mutual funds held in rabbi trusts	0	0
Loans, net	0	0
GGL/SBA loans servicing asset	0	0
Derivative assets	496,978	140,016
Financial liabilities
Non-interest-bearing deposits	12,555,714	9,439,485
Non-time interest-bearing deposits	23,236,436	19,891,711
Time deposits	8,458,264	9,112,459
Total deposits	44,250,414	38,443,655
Federal funds purchased and securities sold under repurchase agreements	0	0
Trading liability for short positions		0
Other short-term borrowings	300,000	1,752,000
Long-term debt	2,351,494	2,185,717
Earnout liability	0	0
Derivative liabilities	194,376	34,732
Level 3
Financial assets
Total cash, cash equivalents, restricted cash, and restricted cash equivalents	0	0
Trading securities	0	0
Investment securities available for sale	1,662	2,105
Loans receivable held-for-sale	634,630	0
Private equity investments	698	3,887
Mutual funds and mutual funds held in rabbi trusts	0	0
Loans, net	39,386,584	36,931,256
GGL/SBA loans servicing asset	3,019	3,040
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
Federal funds purchased and securities sold under repurchase agreements	0	0
Trading liability for short positions		0
Other short-term borrowings	0	0
Long-term debt	0	0
Earnout liability	15,924	11,016
Derivative liabilities	1,755	2,339
Carrying Value
Financial assets
Total cash, cash equivalents, restricted cash, and restricted cash equivalents	1,571,225	1,186,918
Trading securities	4,626	7,212
Investment securities available for sale	7,197,493	6,778,670
Loans receivable held-for-sale	900,936	115,173
Private equity investments	698	19,389
Mutual funds and mutual funds held in rabbi trusts	34,219	32,348
Loans, net	39,325,649	36,881,048
GGL/SBA loans servicing asset	3,019	3,040
Derivative assets	496,978	140,016
Financial liabilities
Non-interest-bearing deposits	12,555,714	9,439,485
Non-time interest-bearing deposits	23,236,436	19,891,711
Time deposits	8,402,430	9,074,308
Total deposits	44,194,580	38,405,504
Federal funds purchased and securities sold under repurchase agreements	225,576	165,690
Trading liability for short positions		1,560
Other short-term borrowings	300,000	1,752,000
Long-term debt	2,327,921	2,153,897
Earnout liability	15,924	11,016
Derivative liabilities	196,131	37,071
Fair Value
Financial assets
Total cash, cash equivalents, restricted cash, and restricted cash equivalents	1,571,225	1,186,918
Trading securities	4,626	7,212
Investment securities available for sale	7,197,493	6,778,670
Loans receivable held-for-sale	900,936	115,173
Private equity investments	698	19,389
Mutual funds and mutual funds held in rabbi trusts	34,219	32,348
Loans, net	39,386,584	36,931,256
GGL/SBA loans servicing asset	3,019	3,040
Derivative assets	496,978	140,016
Financial liabilities
Non-interest-bearing deposits	12,555,714	9,439,485
Non-time interest-bearing deposits	23,236,436	19,891,711
Time deposits	8,458,264	9,112,459
Total deposits	44,250,414	38,443,655
Federal funds purchased and securities sold under repurchase agreements	225,576	165,690
Trading liability for short positions		1,560
Other short-term borrowings	300,000	1,752,000
Long-term debt	2,351,494	2,185,717
Earnout liability	15,924	11,016
Derivative liabilities	$ 196,131	$ 37,071