Loans and Leases (Details 1) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Delinquent loans in loan portfolio
30-89 Days Past Due	$ 4,000	$ 3,000
90 or More Days Past Due	9,600	15,900
Loans held for investment, net	15,556,689	15,455,954
Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	25,869	31,569
90 or More Days Past Due	9,592	15,945
Total Past Due	35,461	47,514
Current	15,424,893	15,300,016
Loans held for investment, net	15,460,354	15,347,530	$ 14,306,961
Real Estate Mortgage | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	10,062	14,284
90 or More Days Past Due	5,854	5,302
Total Past Due	15,916	19,586
Current	5,871,053	5,598,370
Loans held for investment, net	5,886,969	5,617,956	5,630,297
Real Estate Mortgage | Commercial real estate | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	9,218	8,590
90 or More Days Past Due	3,975	3,303
Total Past Due	13,193	11,893
Current	4,365,745	4,341,740
Loans held for investment, net	4,378,938	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	844	5,694
90 or More Days Past Due	1,879	1,999
Total Past Due	2,723	7,693
Current	1,505,308	1,256,630
Loans held for investment, net	1,508,031	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	362	0
Total Past Due	362	364
Current	1,107,874	962,475
Loans held for investment, net	1,108,236	962,839	575,473
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	666,185	578,838
Loans held for investment, net	666,185	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	362	0
Total Past Due	362	364
Current	441,689	383,637
Loans held for investment, net	442,051	384,001
Commercial | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	15,730	16,697
90 or More Days Past Due	3,376	10,643
Total Past Due	19,106	27,340
Current	8,063,572	8,364,220
Loans held for investment, net	8,082,678	8,391,560	7,990,569
Commercial | Cash Flow | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	598	191
90 or More Days Past Due	2,915	1,821
Total Past Due	3,513	2,012
Current	3,129,896	3,105,380
Loans held for investment, net	3,133,409	3,107,392
Commercial | Asset Based | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	500	1,500
90 or More Days Past Due	204	2
Total Past Due	704	1,502
Current	2,390,379	2,607,543
Loans held for investment, net	2,391,083	2,609,045
Commercial | Venture Capital Loans | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	14,381	13,589
90 or More Days Past Due	257	5,769
Total Past Due	14,638	19,358
Current	1,920,311	1,963,798
Loans held for investment, net	1,934,949	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	251	1,417
90 or More Days Past Due	0	3,051
Total Past Due	251	4,468
Current	622,986	687,499
Loans held for investment, net	623,237	691,967
Consumer | Non Purchased Credit Impaired Loans and Leases
Delinquent loans in loan portfolio
30-89 Days Past Due	77	224
90 or More Days Past Due	0	0
Total Past Due	77	224
Current	382,394	374,951
Loans held for investment, net	$ 382,471	$ 375,175	$ 110,622