Loans and Leases (Details 1) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Delinquent loans in loan portfolio
30-89 Days Past Due	$ 700	$ 3,000
90 or More Days Past Due	8,800	15,900
Loans held for investment, net	15,690,517	15,455,954
Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	5,535	31,569
90 or More Days Past Due	8,798	15,945
Total Past Due	14,333	47,514
Current	15,613,690	15,300,016
Loans held for investment, net	15,628,023	15,347,530	$ 14,622,647
Real Estate Mortgage | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	1,967	14,284
90 or More Days Past Due	5,404	5,302
Total Past Due	7,371	19,586
Current	6,123,825	5,598,370
Loans held for investment, net	6,131,196	5,617,956	5,464,941
Real Estate Mortgage | Commercial real estate | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	1,685	8,590
90 or More Days Past Due	3,664	3,303
Total Past Due	5,349	11,893
Current	4,306,899	4,341,740
Loans held for investment, net	4,312,248	4,353,633
Real Estate Mortgage | Residential Real Estate | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	282	5,694
90 or More Days Past Due	1,740	1,999
Total Past Due	2,022	7,693
Current	1,816,926	1,256,630
Loans held for investment, net	1,818,948	1,264,323
Real Estate Construction and Land | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	0	364
90 or More Days Past Due	0	0
Total Past Due	0	364
Current	1,249,222	962,475
Loans held for investment, net	1,249,222	962,839	831,515
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	0	0
90 or More Days Past Due	0	0
Total Past Due	0	0
Current	680,949	578,838
Loans held for investment, net	680,949	578,838
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	364
90 or More Days Past Due	0	0
Total Past Due	0	364
Current	568,273	383,637
Loans held for investment, net	568,273	384,001
Commercial | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	3,282	16,697
90 or More Days Past Due	3,122	10,643
Total Past Due	6,404	27,340
Current	7,855,288	8,364,220
Loans held for investment, net	7,861,692	8,391,560	8,069,687
Commercial | Cash Flow | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	140	191
90 or More Days Past Due	1,484	1,821
Total Past Due	1,624	2,012
Current	2,728,771	3,105,380
Loans held for investment, net	2,730,395	3,107,392
Commercial | Asset Based | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	0	1,500
90 or More Days Past Due	0	2
Total Past Due	0	1,502
Current	2,577,390	2,607,543
Loans held for investment, net	2,577,390	2,609,045
Commercial | Venture Capital Loans | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	3,142	13,589
90 or More Days Past Due	948	5,769
Total Past Due	4,090	19,358
Current	1,955,345	1,963,798
Loans held for investment, net	1,959,435	1,983,156
Commercial | Equipment Finance Commercial Financing Receivable | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	0	1,417
90 or More Days Past Due	690	3,051
Total Past Due	690	4,468
Current	593,782	687,499
Loans held for investment, net	594,472	691,967
Consumer | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	286	224
90 or More Days Past Due	272	0
Total Past Due	558	224
Current	385,355	374,951
Loans held for investment, net	$ 385,913	$ 375,175	$ 256,504