Loans and Leases (Details 3) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	$ 15,690,517	$ 15,455,954
Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	15,628,023	15,347,530	$ 14,622,647
Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	344,777	409,645
Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	15,283,246	14,937,885
Real Estate Mortgage | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	6,131,196	5,617,956	5,464,941
Real Estate Mortgage | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	102,924	117,181
Real Estate Mortgage | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	6,028,272	5,500,775
Real Estate Mortgage | Commercial real estate | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	4,312,248	4,353,633
Real Estate Mortgage | Commercial real estate | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	95,272	99,641
Real Estate Mortgage | Commercial real estate | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	4,216,976	4,253,992
Real Estate Mortgage | Residential Real Estate | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	1,818,948	1,264,323
Real Estate Mortgage | Residential Real Estate | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	7,652	17,540
Real Estate Mortgage | Residential Real Estate | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	1,811,296	1,246,783
Real Estate Construction and Land | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	1,249,222	962,839	831,515
Real Estate Construction and Land | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	0	773
Real Estate Construction and Land | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	1,249,222	962,066
Real Estate Construction and Land | Commercial Real Estate Construction Loan Receivable | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	680,949	578,838
Real Estate Construction and Land | Commercial Real Estate Construction Loan Receivable | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	0	409
Real Estate Construction and Land | Commercial Real Estate Construction Loan Receivable | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	680,949	578,429
Real Estate Construction and Land | Residential Real Estate Construction Financing Receivable | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	568,273	384,001
Real Estate Construction and Land | Residential Real Estate Construction Financing Receivable | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	0	364
Real Estate Construction and Land | Residential Real Estate Construction Financing Receivable | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	568,273	383,637
Commercial | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	7,861,692	8,391,560	8,069,687
Commercial | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	241,396	291,267
Commercial | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	7,620,296	8,100,293
Commercial | Cash Flow | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	2,730,395	3,107,392
Commercial | Cash Flow | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	128,207	177,661
Commercial | Cash Flow | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	2,602,188	2,929,731
Commercial | Asset Based | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	2,577,390	2,609,045
Commercial | Asset Based | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	19,645	28,112
Commercial | Asset Based | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	2,557,745	2,580,933
Commercial | Venture Capital Loans | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	1,959,435	1,983,156
Commercial | Venture Capital Loans | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	62,602	52,646
Commercial | Venture Capital Loans | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	1,896,833	1,930,510
Commercial | Equipment Finance Commercial Financing Receivable | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	594,472	691,967
Commercial | Equipment Finance Commercial Financing Receivable | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	30,942	32,848
Commercial | Equipment Finance Commercial Financing Receivable | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	563,530	659,119
Consumer | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	385,913	375,175	$ 256,504
Consumer | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	457	424
Consumer | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	$ 385,456	$ 374,751