(Summary of nonperforming loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Summary of nonperforming loans
Total nonperforming TDRs	$ 103,111	$ 101,322
Total loans	7,271,147	5,688,230
Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	62,225	50,644
Total accruing loans contractually past due 90 days or more as to interest or principal payments	2,287	2,073
Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total nonperforming TDRs	78,823	77,047
Total loans	4,250,117	3,084,024
Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total nonperforming TDRs	24,288	24,275
Total loans	3,021,030	2,604,206
Commercial [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	28,554	16,418
Total accruing loans contractually past due 90 days or more as to interest or principal payments	364	170
Real estate commercial [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	25,163	24,966
Total accruing loans contractually past due 90 days or more as to interest or principal payments	254	0
Real Estate Construction Loans [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	247	162
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	0
Land Development Loans [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	274	225
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	0
Real estate residential [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	5,557	6,706
Total accruing loans contractually past due 90 days or more as to interest or principal payments	402	557
Consumer Installment Loans [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	451	500
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	0
Home Equity Loans [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	1,979	1,667
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,267	1,346
Nonperforming [Member]
Summary of nonperforming loans
Total nonaccrual loans	62,225	50,644
Total accruing loans contractually past due 90 days or more as to interest or principal payments	2,287	2,073
Total nonperforming TDRs	19,368	18,467
Total loans	83,880	71,184
Nonperforming [Member] \| Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total nonperforming TDRs	16,297	15,271
Nonperforming [Member] \| Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total nonperforming TDRs	3,071	3,196
Nonperforming [Member] \| Commercial [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	28,554	16,418
Total accruing loans contractually past due 90 days or more as to interest or principal payments	364	170
Nonperforming [Member] \| Real estate commercial [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	25,163	24,966
Total accruing loans contractually past due 90 days or more as to interest or principal payments	254	0
Nonperforming [Member] \| Real Estate Construction Loans [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	247	162
Nonperforming [Member] \| Land Development Loans [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	274	225
Nonperforming [Member] \| Real estate residential [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	5,557	6,706
Total accruing loans contractually past due 90 days or more as to interest or principal payments	402	557
Nonperforming [Member] \| Consumer Installment Loans [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	451	500
Nonperforming [Member] \| Home Equity Loans [Member] \| Originated Portfolio Segment [Member]
Summary of nonperforming loans
Total nonaccrual loans	1,979	1,667
Total accruing loans contractually past due 90 days or more as to interest or principal payments	$ 1,267	$ 1,346

Summary of nonperforming loans.

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

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- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5111-111524

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- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

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- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

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