Fair Value Measurements (Details 5) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 184,608	$ 337,965
Interest-earning deposits in financial institutions	111,892	81,705
Securities available-for-sale, at fair value	3,336,992	3,223,830
Available-for-sale Securities	3,336,992	3,223,830
Federal Home Loan Bank stock, at cost	17,901	21,870
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	17,901	21,870
Cost Method Investments	1,175	1,416
Cost Method Investments, Fair Value Disclosure	12,412	3,843
Loans and leases, net	15,395,382	15,298,716
Loans Receivable, Fair Value Disclosure	15,526,920
Derivative Asset	427	694
Deposits, Savings Deposits	13,923,143	13,698,321
Time Deposits	2,407,865	2,172,290
Deposits, Fair Value Disclosure	2,399,793	2,166,187
Borrowings	460,609	905,812
Long-term Debt, Fair Value	460,627	905,838
Subordinated debentures	442,516	440,744
Subordinated Debt Obligations, Fair Value Disclosure	425,914	424,507
Derivative Liability		3,285
Equity warrants		5,497
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	184,608	337,965
Interest-earning deposits in financial institutions	111,892	81,705
Available-for-sale Securities		2,080
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	0	0
Cost Method Investments, Fair Value Disclosure	0	0
Deposits, Savings Deposits	0	0
Deposits, Fair Value Disclosure	0	0
Long-term Debt, Fair Value	456,000	591,000
Subordinated Debt Obligations, Fair Value Disclosure	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0	0
Interest-earning deposits in financial institutions	0	0
Available-for-sale Securities		3,156,475
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	17,901	21,870
Cost Method Investments, Fair Value Disclosure	0	0
Deposits, Savings Deposits	13,923,143	13,698,321
Deposits, Fair Value Disclosure	2,399,793	2,166,187
Long-term Debt, Fair Value	4,627	314,838
Subordinated Debt Obligations, Fair Value Disclosure	425,914	424,507
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0	0
Interest-earning deposits in financial institutions	0	0
Available-for-sale Securities		65,275
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	0	0
Cost Method Investments, Fair Value Disclosure	12,412	3,843
Loans Receivable, Fair Value Disclosure	15,526,920
Deposits, Savings Deposits	0	0
Deposits, Fair Value Disclosure	0	0
Long-term Debt, Fair Value	0	0
Subordinated Debt Obligations, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities	3,336,992	3,223,830
Derivative assets	427	694
Derivative liabilities	3,295	3,285
Equity warrants	5,368	5,497
Fair Value, Measurements, Recurring | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities	1,960	2,080
Derivative assets	0	0
Derivative liabilities	0	0
Equity warrants	0	0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities	3,281,875	3,156,475
Derivative assets	427	694
Derivative liabilities	3,295	3,285
Equity warrants	0	0
Fair Value, Measurements, Recurring | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities	53,157	65,275
Derivative assets	0	0
Derivative liabilities	0	0
Equity warrants	5,368	5,497
Fair Value, Measurements, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		161,215
Fair Value, Measurements, Nonrecurring | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		0
Fair Value, Measurements, Nonrecurring | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		12,885
Fair Value, Measurements, Nonrecurring | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	73,047	148,330
Non Purchased Credit Impaired Loans and Leases | Fair Value, Measurements, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	73,047	149,749
Non Purchased Credit Impaired Loans and Leases | Fair Value, Measurements, Nonrecurring | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Receivable, Fair Value Disclosure	0
Assets, Fair Value Disclosure, Nonrecurring		0
Non Purchased Credit Impaired Loans and Leases | Fair Value, Measurements, Nonrecurring | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Receivable, Fair Value Disclosure	0
Assets, Fair Value Disclosure, Nonrecurring		1,661
Non Purchased Credit Impaired Loans and Leases | Fair Value, Measurements, Nonrecurring | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	$ 73,047	148,088
NonPCI and PCI Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases, net		15,298,716
Loans Receivable, Fair Value Disclosure		15,494,808
NonPCI and PCI Loans | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Receivable, Fair Value Disclosure		0
NonPCI and PCI Loans | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Receivable, Fair Value Disclosure		1,661
NonPCI and PCI Loans | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans Receivable, Fair Value Disclosure		$ 15,493,147