Loans and Leases (Details 3) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	$ 15,556,689	$ 15,455,954
Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	15,460,354	15,347,530	$ 14,306,961
Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	424,399	409,645
Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	15,035,955	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	5,886,969	5,617,956	5,630,297
Real Estate Mortgage | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	109,882	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	5,777,087	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	4,378,938	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	100,202	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	4,278,736	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	1,508,031	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	9,680	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	1,498,351	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	1,108,236	962,839	575,473
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	765	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	1,107,471	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	666,185	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	403	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	665,782	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	442,051	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	362	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	441,689	383,637
Commercial | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	8,082,678	8,391,560	7,990,569
Commercial | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	313,406	291,267
Commercial | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	7,769,272	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	3,133,409	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	175,511	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	2,957,898	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	2,391,083	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	32,285	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	2,358,798	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	1,934,949	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	75,222	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	1,859,727	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	623,237	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	30,388	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	592,849	659,119
Consumer | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	382,471	375,175	$ 110,622
Consumer | Non Purchased Credit Impaired Loans and Leases | Classified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	346	424
Consumer | Non Purchased Credit Impaired Loans and Leases | Nonclassified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment	$ 382,125	$ 374,751