Loans and Leases (Details 3) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	$ 18,846,872	$ 17,957,713
Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	175,912	237,110
Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	322,956	261,398
Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	18,348,004	17,459,205
Mortgages [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	7,972,747	7,918,141
Mortgages [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	42,135	68,255
Mortgages [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	31,781	75,753
Mortgages [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	7,898,831	7,774,133
Mortgages [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	4,202,687	4,824,298
Mortgages [Member] | Commercial Real Estate [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	33,535	57,734
Mortgages [Member] | Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	30,070	74,785
Mortgages [Member] | Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	4,139,082	4,691,779
Mortgages [Member] | Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,770,060	3,093,843
Mortgages [Member] | Residential Real Estate [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	8,600	10,521
Mortgages [Member] | Residential Real Estate [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,711	968
Mortgages [Member] | Residential Real Estate [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,759,749	3,082,354
Real Estate Construction [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,737,802	2,233,656
Real Estate Construction [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	364	442
Real Estate Construction [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,429	8,568
Real Estate Construction [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,736,009	2,224,646
Real Estate Construction [Member] | Commercial Real Estate Construction Loan Receivable [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,082,368	912,583
Real Estate Construction [Member] | Commercial Real Estate Construction Loan Receivable [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	364	442
Real Estate Construction [Member] | Commercial Real Estate Construction Loan Receivable [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	0	7,041
Real Estate Construction [Member] | Commercial Real Estate Construction Loan Receivable [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,082,004	905,100
Real Estate Construction [Member] | Residential Real Estate Construction Financing Receivable [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,655,434	1,321,073
Real Estate Construction [Member] | Residential Real Estate Construction Financing Receivable [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	0	0
Real Estate Construction [Member] | Residential Real Estate Construction Financing Receivable [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,429	1,527
Real Estate Construction [Member] | Residential Real Estate Construction Financing Receivable [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,654,005	1,319,546
Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	7,695,496	7,404,595
Commercial Portfolio Segment [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	132,800	167,214
Commercial Portfolio Segment [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	288,534	176,062
Commercial Portfolio Segment [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	7,274,162	7,061,319
Commercial Portfolio Segment [Member] | Asset Based [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,748,407	3,305,421
Commercial Portfolio Segment [Member] | Asset Based [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	32,223	45,957
Commercial Portfolio Segment [Member] | Asset Based [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	38,936	48,338
Commercial Portfolio Segment [Member] | Asset Based [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	3,677,248	3,211,126
Commercial Portfolio Segment [Member] | Venture Capital Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,179,422	2,038,748
Commercial Portfolio Segment [Member] | Venture Capital Loans [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	35,316	28,731
Commercial Portfolio Segment [Member] | Venture Capital Loans [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	74,813	77,588
Commercial Portfolio Segment [Member] | Venture Capital Loans [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	2,069,293	1,932,429
Commercial Portfolio Segment [Member] | Other Commercial [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,767,667	2,060,426
Commercial Portfolio Segment [Member] | Other Commercial [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	65,261	92,526
Commercial Portfolio Segment [Member] | Other Commercial [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	174,785	50,136
Commercial Portfolio Segment [Member] | Other Commercial [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,527,621	1,917,764
Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	440,827	401,321
Consumer Portfolio Segment [Member] | Classified [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	613	1,199
Consumer Portfolio Segment [Member] | Special Mention [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	1,212	1,015
Consumer Portfolio Segment [Member] | Pass [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	439,002	399,107
Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Past Due [Line Items]
Loans held for investment, net	$ 18,846,872	17,957,713
Non Purchased Credit Impaired Loans and Leases | Mortgages [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		7,918,141
Non Purchased Credit Impaired Loans and Leases | Mortgages [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		4,824,298
Non Purchased Credit Impaired Loans and Leases | Mortgages [Member] | Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		3,093,843
Non Purchased Credit Impaired Loans and Leases | Real Estate Construction [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		2,233,656
Non Purchased Credit Impaired Loans and Leases | Real Estate Construction [Member] | Commercial Real Estate Construction Loan Receivable [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		912,583
Non Purchased Credit Impaired Loans and Leases | Real Estate Construction [Member] | Residential Real Estate Construction Financing Receivable [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		1,321,073
Non Purchased Credit Impaired Loans and Leases | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		7,404,595
Non Purchased Credit Impaired Loans and Leases | Commercial Portfolio Segment [Member] | Asset Based [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		3,305,421
Non Purchased Credit Impaired Loans and Leases | Commercial Portfolio Segment [Member] | Venture Capital Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		2,038,748
Non Purchased Credit Impaired Loans and Leases | Commercial Portfolio Segment [Member] | Other Commercial [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		2,060,426
Non Purchased Credit Impaired Loans and Leases | Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment, net		$ 401,321