Loans and Allowance for Loan Losses, Financing Receivables Past Due (Details) - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		$ 23,731	$ 19,977
Nonaccrual	[1]	33,785	29,359
Current and accruing		7,033,886	6,493,899
Total Loans		7,091,402	6,543,235
Currently performing impaired loans		23,700	19,000
30-89 Days Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		22,108	18,208
90 Days or More Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		1,623	1,769
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		629	0
Nonaccrual	[1]	4,663	5,103
Current and accruing		1,114,819	1,078,394
Total Loans		1,120,111	1,083,497
Commercial Real Estate Owner Occupied [Member] | 30-89 Days Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		629	0
Commercial Real Estate Owner Occupied [Member] | 90 Days or More Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		0	0
Commercial Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		386	0
Nonaccrual	[1]	521	718
Current and accruing		1,346,201	1,191,268
Total Loans		1,347,108	1,191,986
Commercial Real Estate All Other [Member] | 30-89 Days Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		386	0
Commercial Real Estate All Other [Member] | 90 Days or More Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		0	0
Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		6,522	7,776
Nonaccrual	[1]	7,016	9,346
Current and accruing		1,055,082	1,029,395
Total Loans		1,068,620	1,046,517
Consumer Real Estate - Mortgage [Member] | 30-89 Days Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		5,476	6,380
Consumer Real Estate - Mortgage [Member] | 90 Days or More Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		1,046	1,396
Construction and Land Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		8,199	309
Nonaccrual	[1]	7,112	7,607
Current and accruing		801,370	739,781
Total Loans		816,681	747,697
Construction and Land Development [Member] | 30-89 Days Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		8,199	309
Construction and Land Development [Member] | 90 Days or More Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		0	0
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		1,166	4,798
Nonaccrual	[1]	11,917	1,683
Current and accruing		2,478,933	2,222,061
Total Loans		2,492,016	2,228,542
Commercial and Industrial [Member] | 30-89 Days Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		1,166	4,798
Commercial and Industrial [Member] | 90 Days or More Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		0	0
Consumer and Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		6,829	7,094
Nonaccrual	[1]	2,556	4,902
Current and accruing		237,481	233,000
Total Loans		246,866	244,996
Consumer and Other [Member] | 30-89 Days Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		6,252	6,721
Consumer and Other [Member] | 90 Days or More Past Due and Performing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due and accruing		$ 577	$ 373

[1] Approximately $23.7 million and $19.0 million of nonaccrual loans as of June 30, 2016 and December 31, 2015, respectively, were performing pursuant to their contractual terms at those dates.