Loans (Textual) (Details)	9 Months Ended
	Sep. 30, 2016 USD ($) class_of_loan segment director tenant executive	Dec. 31, 2015 USD ($)
Loans (Textual) [Abstract]
Number of portfolio segment (in segment) | segment	2
Number of classes of loans (in class of loan) | class_of_loan	6
Number of minimum tenants under lease of non-owner occupied commercial real estate (in tenant) | tenant	1
Loans	$ 12,715,789,000	$ 7,271,147,000
Minimum due period of loans consider in a nonperforming status	90 days
Total nonaccrual TDR loans	$ 29,500,000	35,900,000
Residential mortgage loans in process of foreclosure	8,100,000	2,900,000
Difference between recorded investment and unpaid principal balance of loan	102,800,000	25,300,000
Confirmed losses (partial charge-offs)	17,400,000	17,100,000
Fair value of discount adjustment	85,400,000	8,200,000
Acquired impaired loans	89,900,000	12,800,000
Performing trouble debt restructuring under impaired loans	48,800,000	47,800,000
Consumer loan portfolio [Member]
Loans (Textual) [Abstract]
Loans	$ 5,282,342,000	3,021,030,000
Maximum due period of loans consider in performing status	90 days
Minimum due period of loans consider in a nonperforming status	90 days
Commercial loan portfolio [Member]
Loans (Textual) [Abstract]
Loans	$ 7,433,447,000	4,250,117,000
Land development loans [Member]
Loans (Textual) [Abstract]
Maximum period for payment of loan	12 months
Residential mortgage [Member]
Loans (Textual) [Abstract]
Period for loan secured under real estate residential security	15 years
Loan-to-value ratio at the time of origination (as a percent)	80.00%
Residential mortgage [Member] | Consumer loan portfolio [Member]
Loans (Textual) [Abstract]
Loans	$ 3,046,959,000	1,429,636,000
Commercial [Member] | Commercial loan portfolio [Member]
Loans (Textual) [Abstract]
Loans	3,159,936,000	$ 1,905,879,000
Minimum value of loan requires group loan authority approval	$ 1,000,000
Number of bank executives and senior officers with credit decision limits similar to group loan authorities (in executive) | executive	6
Minimum value of loan requires executive and senior officer approval	$ 1,500,000
Maximum value of loan requires executive and senior officer approval	3,500,000
Minimum value of loan requires group loan authority approval	1,000,000
Maximum value of loan requires group loan authority approval	$ 10,000,000
Number of members of the board of directors in loan committee (in director) | director	8
Maximum [Member] | Residential mortgage [Member]
Loans (Textual) [Abstract]
Upper limit of number of family residential properties (in tenant) | tenant	4
Maximum [Member] | Commercial [Member] | Commercial loan portfolio [Member]
Loans (Textual) [Abstract]
Other loans requiring director loan committee approval depending on risk rating and credit action required	$ 10,000,000
Minimum [Member] | Residential mortgage [Member]
Loans (Textual) [Abstract]
Lower limit of number of family residential properties (in tenant) | tenant	1
Minimum [Member] | Commercial [Member] | Commercial loan portfolio [Member]
Loans (Textual) [Abstract]
Minimum value of loans requiring only director loan committee approval	$ 10,000,000
Minimum value of loans depending on risk rating and requires credit action from board of directors	15,000,000
Foreign [Member]
Loans (Textual) [Abstract]
Loans	$ 0