Schedule of Recorded Investment in Past Due Loans by Class (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Mortgage loans held for sale	$ 56,663		$ 56,663		$ 40,861
Loans held for investment	4,449,699		4,449,699		4,303,992
Total loans	4,506,362	4,297,364	4,506,362	4,297,364	4,344,853
Interest Income on Non-Accrual Loans if Accrued	1,061	1,299	2,182	2,651
Commercial real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	5,343		5,343		5,924
60 to 89 Days Past Due	2,540		2,540		2,472
Greater than 90 Days Past Due	40		40		22
Total Loans 30 or More Days Past Due	7,923		7,923		8,418
Current Loans	1,418,602		1,418,602		1,391,823
Non-accrual Loans	38,422		38,422		48,933
Loans held for investment	1,464,947		1,464,947		1,449,174
Land acquisition & development construction real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	782		782		1,062
60 to 89 Days Past Due	123		123		468
Greater than 90 Days Past Due	0		0		38
Total Loans 30 or More Days Past Due	905		905		1,568
Current Loans	180,094		180,094		188,074
Non-accrual Loans	11,290		11,290		16,269
Loans held for investment	192,289		192,289		205,911
Residential construction real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	90		90		933
60 to 89 Days Past Due	1,226		1,226		250
Greater than 90 Days Past Due	0		0		0
Total Loans 30 or More Days Past Due	1,316		1,316		1,183
Current Loans	80,152		80,152		73,933
Non-accrual Loans	653		653		1,372
Loans held for investment	82,121		82,121		76,488
Commercial construction real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	0		0		584
60 to 89 Days Past Due	0		0		0
Greater than 90 Days Past Due	0		0		0
Total Loans 30 or More Days Past Due	0		0		584
Current Loans	84,019		84,019		68,427
Non-accrual Loans	2,580		2,580		225
Loans held for investment	86,599		86,599		69,236
Total construction loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	872		872		2,579
60 to 89 Days Past Due	1,349		1,349		718
Greater than 90 Days Past Due	0		0		38
Total Loans 30 or More Days Past Due	2,221		2,221		3,335
Current Loans	344,265		344,265		330,434
Non-accrual Loans	14,523		14,523		17,866
Loans held for investment	361,009		361,009		351,635
Residential real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	3,493		3,493		3,630
60 to 89 Days Past Due	823		823		206
Greater than 90 Days Past Due	665		665		1,162
Total Loans 30 or More Days Past Due	4,981		4,981		4,998
Current Loans	884,261		884,261		856,800
Non-accrual Loans	5,260		5,260		6,114
Loans held for investment	894,502		894,502		867,912
Agricultural real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	29		29		328
60 to 89 Days Past Due	72		72		646
Greater than 90 Days Past Due	0		0		0
Total Loans 30 or More Days Past Due	101		101		974
Current Loans	155,228		155,228		163,986
Non-accrual Loans	7,099		7,099		8,574
Loans held for investment	162,428		162,428		173,534
Total real estate loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	9,737		9,737		12,461
60 to 89 Days Past Due	4,784		4,784		4,042
Greater than 90 Days Past Due	705		705		1,222
Total Loans 30 or More Days Past Due	15,226		15,226		17,725
Current Loans	2,802,356		2,802,356		2,743,043
Non-accrual Loans	65,304		65,304		81,487
Loans held for investment	2,882,886		2,882,886		2,842,255
Indirect consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	2,467		2,467		3,303
60 to 89 Days Past Due	404		404		430
Greater than 90 Days Past Due	15		15		9
Total Loans 30 or More Days Past Due	2,886		2,886		3,742
Current Loans	508,777		508,777		471,906
Non-accrual Loans	400		400		364
Loans held for investment	512,063		512,063		476,012
Other consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	780		780		925
60 to 89 Days Past Due	210		210		130
Greater than 90 Days Past Due	16		16		1
Total Loans 30 or More Days Past Due	1,006		1,006		1,056
Current Loans	131,864		131,864		131,508
Non-accrual Loans	734		734		475
Loans held for investment	133,604		133,604		133,039
Credit card consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	281		281		364
60 to 89 Days Past Due	239		239		187
Greater than 90 Days Past Due	335		335		515
Total Loans 30 or More Days Past Due	855		855		1,066
Current Loans	60,496		60,496		61,451
Non-accrual Loans	17		17		19
Loans held for investment	61,368		61,368		62,536
Total consumer loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	3,528		3,528		4,592
60 to 89 Days Past Due	853		853		747
Greater than 90 Days Past Due	366		366		525
Total Loans 30 or More Days Past Due	4,747		4,747		5,864
Current Loans	701,137		701,137		664,865
Non-accrual Loans	1,151		1,151		858
Loans held for investment	707,035		707,035		671,587
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	3,223		3,223		2,791
60 to 89 Days Past Due	718		718		1,186
Greater than 90 Days Past Due	325		325		563
Total Loans 30 or More Days Past Due	4,266		4,266		4,540
Current Loans	710,886		710,886		660,035
Non-accrual Loans	12,330		12,330		11,969
Loans held for investment	727,482		727,482		676,544
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	1,390		1,390		453
60 to 89 Days Past Due	17		17		672
Greater than 90 Days Past Due	125		125		0
Total Loans 30 or More Days Past Due	1,532		1,532		1,125
Current Loans	128,367		128,367		110,622
Non-accrual Loans	381		381		125
Loans held for investment	130,280		130,280		111,872
Other, including overdrafts
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	0		0		0
60 to 89 Days Past Due	0		0		0
Greater than 90 Days Past Due	1		1		0
Total Loans 30 or More Days Past Due	1		1		0
Current Loans	2,015		2,015		1,734
Non-accrual Loans	0		0		0
Loans held for investment	2,016		2,016		1,734
Loans held for investment
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	17,878		17,878		20,297
60 to 89 Days Past Due	6,372		6,372		6,647
Greater than 90 Days Past Due	1,522		1,522		2,310
Total Loans 30 or More Days Past Due	25,772		25,772		29,254
Current Loans	4,344,761		4,344,761		4,180,299
Non-accrual Loans	79,166		79,166		94,439
Loans held for investment	4,449,699		4,449,699		4,303,992
Mortgage loans originated for sale
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	0		0		0
60 to 89 Days Past Due	0		0		0
Greater than 90 Days Past Due	0		0		0
Total Loans 30 or More Days Past Due	0		0		0
Current Loans	56,663		56,663		40,861
Non-accrual Loans	0		0		0
Total loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
30 to 59 Days Past Due	17,878		17,878		20,297
60 to 89 Days Past Due	6,372		6,372		6,647
Greater than 90 Days Past Due	1,522		1,522		2,310
Total Loans 30 or More Days Past Due	25,772		25,772		29,254
Current Loans	4,401,424		4,401,424		4,221,160
Non-accrual Loans	79,166		79,166		94,439
Total loans	$ 4,506,362		$ 4,506,362		$ 4,344,853