Loans (Summary of Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Summary of loans under portfolio
Loans	$ 12,990,779	$ 7,271,147
Deferred costs	14,800	10,700
Commercial
Summary of loans under portfolio
Loans		1,905,879
Commercial real estate
Summary of loans under portfolio
Loans		2,112,162
Real estate construction and land development
Summary of loans under portfolio
Loans		232,076
Residential mortgage
Summary of loans under portfolio
Loans		1,429,636
Consumer installment
Summary of loans under portfolio
Loans		877,457
Home equity
Summary of loans under portfolio
Loans		713,937
Commercial Originated Portfolio
Summary of loans under portfolio
Loans	4,105,049	3,130,721
Commercial Originated Portfolio | Commercial
Summary of loans under portfolio
Loans	1,901,526	1,521,515
Commercial Originated Portfolio | Commercial real estate
Summary of loans under portfolio
Loans	1,921,799	1,424,059
Commercial Originated Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	281,724	185,147
Consumer Originated Portfolio
Summary of loans under portfolio
Loans	3,353,352	2,677,213
Consumer Originated Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	1,475,342	1,216,975
Consumer Originated Portfolio | Consumer installment
Summary of loans under portfolio
Loans	1,282,588	869,426
Consumer Originated Portfolio | Home equity
Summary of loans under portfolio
Loans	595,422	590,812
Originated Portfolio
Summary of loans under portfolio
Loans	7,458,401	5,807,934
Originated Portfolio | Commercial
Summary of loans under portfolio
Loans	1,901,526	1,521,515
Originated Portfolio | Commercial real estate
Summary of loans under portfolio
Loans	1,921,799	1,424,059
Originated Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	281,724	185,147
Originated Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	1,475,342	1,216,975
Originated Portfolio | Consumer installment
Summary of loans under portfolio
Loans	1,282,588	869,426
Originated Portfolio | Home equity
Summary of loans under portfolio
Loans	595,422	590,812
Commercial Acquired Portfolio
Summary of loans under portfolio
Loans	3,489,163	1,119,396
Commercial Acquired Portfolio | Commercial
Summary of loans under portfolio
Loans	1,315,774	384,364
Commercial Acquired Portfolio | Commercial real estate
Summary of loans under portfolio
Loans	2,051,341	688,103
Commercial Acquired Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	122,048	46,929
Consumer Acquired Portfolio
Summary of loans under portfolio
Loans	2,043,215	343,817
Consumer Acquired Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	1,611,132	212,661
Consumer Acquired Portfolio | Consumer installment
Summary of loans under portfolio
Loans	151,296	8,031
Consumer Acquired Portfolio | Home equity
Summary of loans under portfolio
Loans	280,787	123,125
Acquired Portfolio
Summary of loans under portfolio
Loans	5,532,378	1,463,213
Commercial Loan Portfolio
Summary of loans under portfolio
Loans	7,594,212	4,250,117
Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	3,217,300
Commercial Loan Portfolio | Commercial real estate
Summary of loans under portfolio
Loans	3,973,140
Commercial Loan Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	403,772
Consumer Loan Portfolio
Summary of loans under portfolio
Loans	5,396,567	3,021,030
Consumer Loan Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	3,086,474	1,429,636
Consumer Loan Portfolio | Consumer installment
Summary of loans under portfolio
Loans	1,433,884	877,457
Consumer Loan Portfolio | Home equity
Summary of loans under portfolio
Loans	$ 876,209	$ 713,937