Goodwill and Intangible Assets (Details)			12 Months Ended
	Oct. 02, 2014 USD ($)	Jan. 02, 2014 USD ($)	Dec. 31, 2015 USD ($) $ / loans Rate	Dec. 31, 2014 USD ($) $ / loans Rate	Dec. 31, 2013 USD ($)
Servicing Asset at Amortized Cost [Line Items]
Servicing Asset at Amortized Cost			$ 19,351,000	$ 16,688,000	$ 16,000
Servicing Asset at Amortized Cost, Additions			5,910,000	727,000
Valuation Allowance for Impairment of Recognized Servicing Assets, Balance			95,000	850,000	0
Residential Mortgage Loans Serviced			$ 2,150,000,000	$ 1,950,000,000
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Prepayment Speed | Rate			11.01%	14.25%
Contractually Specified Servicing Fees, Late Fees, and Ancillary Fees Earned in Exchange for Servicing Financial Assets			$ 5,400,000	$ 600,000	300,000
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Cost to Service Loans | $ / loans			56,610.00	56,020.00
Amortization			$ (4,002,000)	$ (919,000)	(205,000)
Goodwill [Roll Forward]
Beginning goodwill		$ 102,625,000	139,773,000	102,625,000
Ending goodwill			139,773,000	139,773,000	102,625,000
Finite-lived Intangible Assets [Roll Forward]
Beginning balance			106,610,000
Finite Lived Intangible Assets Removed Due To Branch Sale			(85,000)	0
Amortization			(18,892,000)	(6,955,000)
Ending balance			90,986,000	106,610,000
Finite-Lived Intangible Assets [Abstract]
Gross balance			115,201,000	114,596,000
Accumulated amortization			(43,566,000)	(24,674,000)
Carrying value			71,635,000	89,922,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2015			16,440,000
2016			14,075,000
2017			11,710,000
2018			9,457,000
2019			7,492,000
Other Intangible Assets, Net			71,635,000	89,922,000	$ 1,247,000
Valuation Allowance for Impairment of Recognized Servicing Assets, Provisions (Recoveries)			755,000	(850,000)
Capitol City Bank and Trust
Finite-lived Intangible Assets [Roll Forward]
Intangible assets acquired			690,000	0
1st Financial
Servicing Asset at Amortized Cost [Line Items]
Finite-Lived Core Deposits, Gross			3,800,000
Servicing Asset at Fair Value, Additions			0	148,000
Goodwill [Roll Forward]
Goodwill acquired		$ 32,915,000	$ 0	32,915,000
Useful life			3 months
Finite-lived Intangible Assets [Roll Forward]
Intangible assets acquired			$ 0	3,780,000
Bancorporation
Servicing Asset at Amortized Cost [Line Items]
Finite-Lived Core Deposits, Gross			91,900,000
Servicing Asset at Fair Value, Additions			0	17,566,000
Goodwill [Roll Forward]
Goodwill acquired	$ 4,233,000		$ 0	4,233,000
Useful life			5 years 6 months
Finite-lived Intangible Assets [Roll Forward]
Intangible assets acquired			$ 0	$ 91,850,000
Conventional fixed loans
Servicing Asset at Amortized Cost [Line Items]
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate | Rate			9.31%	7.20%
All loans and leases excluding conventional fixed loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate | Rate			10.31%	9.20%
Core deposits | Minimum
Goodwill [Roll Forward]
Useful life			2 years
Core deposits | Maximum
Goodwill [Roll Forward]
Useful life			9 years