Loans and Leases (Details 2) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Financing Receivable, Impaired [Line Items]
Nonaccrual	$ 171,085	$ 129,019
Loans held for investment	14,742,846	14,478,254
Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	171,085	129,019
Loans held for investment	14,622,647	14,289,209	$ 12,258,916
Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	14,451,562	14,160,190
Real Estate Mortgage | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	79,695	57,277
Loans held for investment	5,464,941	5,688,063	5,505,087
Real Estate Mortgage | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	5,385,246	5,630,786
Real Estate Mortgage | Commercial real estate | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	74,606	52,363
Loans held for investment	4,278,832	4,551,958
Real Estate Mortgage | Commercial real estate | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	4,204,226	4,499,595
Real Estate Mortgage | Residential Real Estate | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	5,089	4,914
Loans held for investment	1,186,109	1,136,105
Real Estate Mortgage | Residential Real Estate | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	1,181,020	1,131,191
Real Estate Construction and Land | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	1,611	372
Loans held for investment	831,515	527,720	372,480
Real Estate Construction and Land | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	829,904	527,348
Real Estate Construction and Land | Commercial Real Estate Construction Loan Receivable | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	1,245	0
Loans held for investment	508,411	343,360
Real Estate Construction and Land | Commercial Real Estate Construction Loan Receivable | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	507,166	343,360
Real Estate Construction and Land | Residential Real Estate Construction Financing Receivable | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	366	372
Loans held for investment	323,104	184,360
Real Estate Construction and Land | Residential Real Estate Construction Financing Receivable | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	322,738	183,988
Commercial | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	89,573	69,839
Loans held for investment	8,069,687	7,952,577	6,251,528
Commercial | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	7,980,114	7,882,738
Commercial | Cash Flow | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	27,831	15,800
Loans held for investment	3,065,491	3,062,268
Commercial | Cash Flow | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	3,037,660	3,046,468
Commercial | Asset Based | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	4,044	2,505
Loans held for investment	2,571,801	2,547,533
Commercial | Asset Based | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	2,567,757	2,545,028
Commercial | Venture Capital Loans | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	10,782	124
Loans held for investment	1,761,612	1,452,427
Commercial | Venture Capital Loans | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	1,750,830	1,452,303
Commercial | Equipment Finance Commercial Financing Receivable | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	46,916	51,410
Loans held for investment	670,783	890,349
Commercial | Equipment Finance Commercial Financing Receivable | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	623,867	838,939
Consumer | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Nonaccrual	206	1,531
Loans held for investment	256,504	120,849	$ 129,821
Consumer | Performing | Non Purchased Credit Impaired Loans and Leases
Financing Receivable, Impaired [Line Items]
Loans held for investment	$ 256,298	$ 119,318