Summary of Significant Accounting Policies, Subsequent Events (Details)		1 Months Ended
	Jan. 22, 2017 USD ($) Director $ / shares shares	Jan. 31, 2017 USD ($) shares	Jan. 13, 2017 shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares
Subsequent Event [Line Items]
Common stock, par value (in dollars per share) | $ / shares				$ 1.00	$ 1.00
Common stock, shares outstanding (in shares) | shares				46,359,377	40,906,064
Subordinated notes issued				$ 350,768,050	$ 141,605,504
Subsequent Event [Member] | 2017 Public Offering [Member]
Subsequent Event [Line Items]
Common stock issued in initial public offering (in shares) | shares		3,220,000
Net proceeds after deducting underwriting discounts and comissions		$ 191,200,000
Subsequent Event [Member] | 2017 Public Offering [Member] | Pinnacle Bank [Member]
Subsequent Event [Line Items]
Net proceeds after deducting underwriting discounts and comissions		$ 185,000,000
Subsequent Event [Member] | BNC Bancorp, a North Carolina Corporation (BNC) [Member]
Subsequent Event [Line Items]
Conversion of stock (in shares) | shares	0.5235
Common stock, par value (in dollars per share) | $ / shares	$ 0
Common stock, shares outstanding (in shares) | shares			52,181,073
Outsatnding restricted stock awards and restricted stock award units (in shares) | shares			901,726
Outstanding stock option (in shares) | shares			66,443
Number of trading days ending immediately preceding the closing date	10 days
Termination fee	$ 66,000,000
Total number of members of their respective Board of Directors | Director	18
Number of additional members of the Board of Directors | Director	3
Subordinated notes issued	$ 60,000,000
Subordinated notes, maturity date	Oct. 31, 2024
Subordinated notes, interest rate	5.50%
Aggregate principal amount of subordinated debentures	$ 50,500,000
Consummation of merger, exceeds the total assets	$ 15,000,000,000