Fair Value - Estimated fair value and related carrying amount, of the Company’s financial instruments - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Jan. 03, 2017	Dec. 31, 2016
Financial assets:
Loans held for sale	$ 46,988	$ 34,933		$ 50,572
Financial liabilities:
Federal Funds Purchased and Securities Sold under Agreements to Repurchase.	352,431	312,034	$ 1,014	313,773
Increase (Decrease) in Loans Held-for-sale	176,946	165,197
Other borrowings	107,988	55,210		55,358
Carrying Amount
Financial assets:
Cash and cash equivalents	663,126	697,277		374,448
Investment securities	1,400,609	995,506		1,014,981
Loans held for sale	46,988	34,933		50,572
Loans, net of allowance for loan losses	7,868,840	6,129,228		6,643,326
FDIC receivable for loss share agreements		2,091
Interest Receivable	22,823	18,023		18,618
Mortgage servicing rights	30,063	23,697		29,037
Interest rate swap - non-designated hedge	133			203
Other derivative financial instruments (Mortgage - banking related)	2,280	3,439		2,403
Financial liabilities:
Deposits	9,033,438	7,161,948		7,334,423
Federal Funds Purchased and Securities Sold under Agreements to Repurchase.	352,431	312,034		313,773
Other borrowings	107,988	55,210		55,358
Interest Payable	1,452	1,926		1,359
Interest rate swap - non-designated hedge	121			181
Interest rate swap - cash flow hedge	426	797		498
Other derivative financial instruments (Mortgage banking related)	387	611		51
Fair Value.
Financial assets:
Cash and cash equivalents	663,126	697,277		374,448
Investment securities	1,400,731	995,866		1,015,137
Loans held for sale	46,988	34,933		50,572
Loans, net of allowance for loan losses	7,936,291	6,257,082		6,649,575
FDIC receivable for loss share agreements		(4,224)
Interest Receivable	22,823	18,023		18,618
Mortgage servicing rights	30,063	23,697		29,037
Interest rate swap - non-designated hedge	133			203
Other derivative financial instruments (Mortgage - banking related)	2,280	3,439		2,403
Financial liabilities:
Deposits	8,462,144	6,950,947		6,935,867
Federal Funds Purchased and Securities Sold under Agreements to Repurchase.	352,431	312,034		313,773
Other borrowings	109,470	49,230		54,379
Interest Payable	1,452	1,926		1,359
Interest rate swap - non-designated hedge	121			181
Interest rate swap - cash flow hedge	426	797		498
Other derivative financial instruments (Mortgage banking related)	387	611		51
Commitments to extend credit | Fair Value.
Financial liabilities:
Commitments to extend credit	16,756			1,587
Standby letters of credit and financial guarantees | Fair Value.
Financial liabilities:
Commitments to extend credit		33,260
Quoted Prices In Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and cash equivalents	663,126	697,277		374,448
Investment securities	16,267	12,075		12,041
Significant Other Observable Inputs (Level 2)
Financial assets:
Investment securities	1,384,464	983,791		1,003,096
Loans held for sale	46,988	34,933		50,572
Interest Receivable	5,558	3,964		3,642
Interest rate swap - non-designated hedge	133			203
Other derivative financial instruments (Mortgage - banking related)	2,280	3,439		2,403
Financial liabilities:
Deposits	8,462,144	6,950,947		6,935,867
Federal Funds Purchased and Securities Sold under Agreements to Repurchase.	352,431	312,034		313,773
Other borrowings	109,470	49,230		54,379
Interest Payable	1,452	1,926		1,359
Interest rate swap - non-designated hedge	121			181
Interest rate swap - cash flow hedge	426	797		498
Other derivative financial instruments (Mortgage banking related)	387	611		51
Significant Other Observable Inputs (Level 2) | Commitments to extend credit
Financial liabilities:
Commitments to extend credit	16,756			1,587
Significant Other Observable Inputs (Level 2) | Standby letters of credit and financial guarantees
Financial liabilities:
Commitments to extend credit		33,260
Significant Unobservable Inputs (Level 3)
Financial assets:
Loans, net of allowance for loan losses	7,936,291	6,257,082		6,649,575
FDIC receivable for loss share agreements		(4,224)
Interest Receivable	17,265	14,059		14,976
Mortgage servicing rights	30,063	23,697		29,037
Recurring basis
Financial assets:
Loans held for sale	46,988	34,933		50,572
Mortgage servicing rights	30,063	23,697		29,037
Recurring basis | Significant Other Observable Inputs (Level 2)
Financial assets:
Loans held for sale	46,988	34,933		50,572
Recurring basis | Significant Unobservable Inputs (Level 3)
Financial assets:
Mortgage servicing rights	$ 30,063	$ 23,697		$ 29,037