Schedule of Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Certain Loans and Debt Securities Acquired in Transfer, Allowance for Credit Losses Due to Subsequent Impairment					$ 701	$ 427
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 76,231	$ 79,924	$ 76,214	$ 76,817
Provision charged to operating expense	2,355	2,550	4,085	6,550
Less loans charged-off	(4,489)	(3,441)	(8,162)	(7,743)
Add back recoveries of loans previously charged-off	1,604	1,307	3,564	4,716
Ending balance	75,701	80,340	75,701	80,340
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment					16,316	13,954
Loans collectively evaluated for impairment					59,385	62,260
Ending balance	76,231	79,924	76,214	76,817	75,701	76,214
Total loans:
Individually evaluated for impairment					97,231	104,691
Individually evaluated for impairment					7,428,359	5,312,059
Total loans					7,525,590	5,416,750
Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	33,092	36,652	28,625	52,296
Provision charged to operating expense	1,078	(4,059)	5,465	(20,140)
Less loans charged-off	(980)	(523)	(1,243)	(2,445)
Add back recoveries of loans previously charged-off	308	211	651	2,570
Ending balance	33,498	32,281	33,498	32,281
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment					8,898	4,588
Loans collectively evaluated for impairment					24,600	24,037
Ending balance	33,092	36,652	28,625	52,296	33,498	28,625
Total loans:
Individually evaluated for impairment					62,323	68,632
Individually evaluated for impairment					5,064,637	3,445,451
Total loans					5,126,960	3,514,083
Total consumer loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	8,368	5,256	7,711	5,144
Provision charged to operating expense	489	2,123	2,537	3,352
Less loans charged-off	(2,412)	(1,712)	(5,008)	(3,604)
Add back recoveries of loans previously charged-off	1,109	648	2,314	1,423
Ending balance	7,554	6,315	7,554	6,315
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment					8	0
Loans collectively evaluated for impairment					7,546	7,711
Ending balance	8,368	5,256	7,711	5,144	7,554	7,711
Total loans:
Individually evaluated for impairment					25	0
Individually evaluated for impairment					1,030,369	970,266
Total loans					1,030,394	970,266
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	33,562	36,252	38,092	18,775
Provision charged to operating expense	453	4,313	(3,675)	22,003
Less loans charged-off	(1,049)	(1,018)	(1,841)	(1,506)
Add back recoveries of loans previously charged-off	158	448	548	723
Ending balance	33,124	39,995	33,124	39,995
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment					6,882	9,254
Loans collectively evaluated for impairment					26,242	28,838
Ending balance	33,562	36,252	38,092	18,775	33,124	38,092
Total loans:
Individually evaluated for impairment					31,903	32,397
Individually evaluated for impairment					1,178,966	765,545
Total loans					1,210,869	797,942
Agriculture
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,209	1,764	1,786	602
Provision charged to operating expense	335	173	(242)	1,335
Less loans charged-off	(48)	(188)	(70)	(188)
Add back recoveries of loans previously charged-off	29	0	51	0
Ending balance	1,525	1,749	1,525	1,749
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment					528	112
Loans collectively evaluated for impairment					997	1,674
Ending balance	1,209	1,764	1,786	602	1,525	1,786
Total loans:
Individually evaluated for impairment					2,980	3,662
Individually evaluated for impairment					146,149	129,196
Total loans					149,129	132,858
Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	0	0	0
Provision charged to operating expense	0	0	0	0
Less loans charged-off	0	0	0	0
Add back recoveries of loans previously charged-off	0	0	0	0
Ending balance	0	0	0	0
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment					0	0
Loans collectively evaluated for impairment					0	0
Ending balance	$ 0	$ 0	$ 0	$ 0	0	0
Total loans:
Individually evaluated for impairment					0	0
Individually evaluated for impairment					8,238	1,601
Total loans					$ 8,238	$ 1,601