Loans and Leases (Details 1) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Delinquent loans in loan portfolio
30-89 Days Past Due	$ 13,200	$ 3,600
90 or More Days Past Due	11,900	16,800
Loans held for investment, net	14,742,846	14,478,254
Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	22,014	10,622
90 or More Days Past Due	11,884	17,508
Total Past Due	33,898	28,130
Current	14,588,749	14,261,079
Loans held for investment, net	14,622,647	14,289,209	$ 12,258,916
Real Estate Mortgage | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	10,755	7,338
90 or More Days Past Due	8,292	13,980
Total Past Due	19,047	21,318
Current	5,445,894	5,666,745
Loans held for investment, net	5,464,941	5,688,063	5,505,087
Real Estate Mortgage | Commercial real estate | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	10,489	3,947
90 or More Days Past Due	5,772	13,075
Total Past Due	16,261	17,022
Current	4,262,571	4,534,936
Loans held for investment, net	4,278,832	4,551,958
Real Estate Mortgage | Residential Real Estate | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	266	3,391
90 or More Days Past Due	2,520	905
Total Past Due	2,786	4,296
Current	1,183,323	1,131,809
Loans held for investment, net	1,186,109	1,136,105
Real Estate Construction and Land | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	1,245	0
90 or More Days Past Due	0	0
Total Past Due	1,245	0
Current	830,270	527,720
Loans held for investment, net	831,515	527,720	372,480
Real Estate Construction and Land | Commercial Real Estate Construction Loan Receivable | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	1,245	0
90 or More Days Past Due	0	0
Total Past Due	1,245	0
Current	507,166	343,360
Loans held for investment, net	508,411	343,360
Real Estate Construction and Land | Residential Real Estate Construction Financing Receivable | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	0	0
90 or More Days Past Due	0	0
Total Past Due	0	0
Current	323,104	184,360
Loans held for investment, net	323,104	184,360
Commercial | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	10,014	2,658
90 or More Days Past Due	3,588	2,221
Total Past Due	13,602	4,879
Current	8,056,085	7,947,698
Loans held for investment, net	8,069,687	7,952,577	6,251,528
Commercial | Cash Flow | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	66	2,048
90 or More Days Past Due	2,128	1,427
Total Past Due	2,194	3,475
Current	3,063,297	3,058,793
Loans held for investment, net	3,065,491	3,062,268
Commercial | Asset Based | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	6,644	1
90 or More Days Past Due	15	0
Total Past Due	6,659	1
Current	2,565,142	2,547,532
Loans held for investment, net	2,571,801	2,547,533
Commercial | Venture Capital Loans | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	0	250
90 or More Days Past Due	1,095	700
Total Past Due	1,095	950
Current	1,760,517	1,451,477
Loans held for investment, net	1,761,612	1,452,427
Commercial | Equipment Finance Commercial Financing Receivable | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	3,304	359
90 or More Days Past Due	350	94
Total Past Due	3,654	453
Current	667,129	889,896
Loans held for investment, net	670,783	890,349
Consumer | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	0	626
90 or More Days Past Due	4	1,307
Total Past Due	4	1,933
Current	256,500	118,916
Loans held for investment, net	$ 256,504	$ 120,849	$ 129,821