Loans and Leases (Details Textual)	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($) Contract	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) Contract	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Financing Receivable, Impaired [Line Items]
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 0	$ 200,000.0	$ 0	$ 200,000.0
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0		0		$ 0
Non-PCI nonaccrual loans	107,190,000		107,190,000		83,621,000
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	22,100,000		22,100,000		18,800,000
Financing Receivable Recorded Investment Thirty to Eighty Nine Days Past Due	2,600,000		2,600,000		8,700,000
Financing Receivable Recorded Investment Nonaccrual Status Current	82,400,000		82,400,000		56,100,000
NonCovered [Member]
Financing Receivable, Impaired [Line Items]
Non-PCI nonaccrual loans					11,591,641,000
Financing Receivable, Recorded Investment, Equal to Greater than 90 Days Past Due	22,121,000		22,121,000		18,818,000
Financing Receivable Recorded Investment Thirty to Eighty Nine Days Past Due	5,886,000		5,886,000		19,406,000
Financing Receivable, Recorded Investment, Nonaccrual Status	107,190,000		107,190,000		$ 83,621,000
Loans and Leases Related to the Oil and Gas Industries
Financing Receivable, Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 47,900,000		$ 47,900,000
Nonperforming Financing Receivable [Member] | Loans and Leases Related to the Oil and Gas Industries
Financing Receivable, Impaired [Line Items]
Financing Receivable, Number Of Contracts | Contract	4		4