Loans (Summary of Nonperforming Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Summary of nonperforming loans
Total TDRs	$ 95,292	$ 103,111
Total loans	12,715,789	7,271,147
Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	72,263	78,823
Total loans	7,433,447	4,250,117
Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	23,029	24,288
Total loans	5,282,342	3,021,030
Commercial [Member] | Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total loans	3,159,936	1,905,879
Commercial real estate [Member] | Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total loans	3,773,017	2,112,162
Real estate construction and land development [Member] | Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total loans	500,494	232,076
Residential mortgage [Member] | Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total loans	3,046,959	1,429,636
Consumer Installment Loans [Member] | Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total loans	1,335,707	877,457
Home Equity Loans [Member] | Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total loans	899,676	713,937
Nonperforming [Member]
Summary of nonperforming loans
Total nonaccrual loans	41,297	62,225
Total accruing loans contractually past due 90 days or more as to interest or principal payments	3,402	2,287
Total TDRs	16,952	19,368
Total loans	61,651	83,880
Nonperforming [Member] | Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	15,261	16,297
Nonperforming [Member] | Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	1,691	3,071
Nonperforming [Member] | Commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	13,742	28,554
Total accruing loans contractually past due 90 days or more as to interest or principal payments	221	364
Nonperforming [Member] | Commercial real estate [Member]
Summary of nonperforming loans
Total nonaccrual loans	19,914	25,163
Total accruing loans contractually past due 90 days or more as to interest or principal payments	739	254
Nonperforming [Member] | Real estate construction and land development [Member]
Summary of nonperforming loans
Total nonaccrual loans	80	521
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,439	0
Nonperforming [Member] | Residential mortgage [Member]
Summary of nonperforming loans
Total nonaccrual loans	5,119	5,557
Total accruing loans contractually past due 90 days or more as to interest or principal payments	375	402
Nonperforming [Member] | Consumer Installment Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	378	451
Nonperforming [Member] | Home Equity Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	2,064	1,979
Total accruing loans contractually past due 90 days or more as to interest or principal payments	$ 628	$ 1,267