Portfolio Loans Not Covered by Loss Share ("Non-covered") - Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Summary of Recorded Investment in Non-covered Loans by Portfolio Class and Category Based on Impairment Method [Line Items]
Impaired Financing Receivable, Interest Income, Accrual Method	$ 6,000	$ 29,000
Loans - Ending Balance:
Total	2,173,988,000		2,137,313,000
Non-Covered Loans
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	2,270,000		1,550,000
Collectively evaluated for impairment	25,635,000		25,739,000
Total	27,905,000		27,289,000
Loans - Ending Balance:
Individually evaluated for Impairment	16,115,000		20,840,000
Collectively evaluated for impairment	2,157,873,000		2,116,473,000
Total	2,172,811,000		2,136,292,000
Total	2,173,988,000		2,137,313,000
Non-Covered Loans | Commercial & Industrial
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	1,472,000		736,000
Collectively evaluated for impairment	11,386,000		11,510,000
Total	12,858,000		12,246,000
Loans - Ending Balance:
Individually evaluated for Impairment	5,046,000		3,380,000
Collectively evaluated for impairment	1,055,322,000		1,038,196,000
Total	1,060,368,000		1,041,576,000
Non-Covered Loans | Commercial Real Estate Owner Occupied
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	401,000		107,000
Collectively evaluated for impairment	3,956,000		3,989,000
Total	4,357,000		4,096,000
Loans - Ending Balance:
Individually evaluated for Impairment	2,232,000		606,000
Collectively evaluated for impairment	365,068,000		341,025,000
Total	367,300,000		341,631,000
Non-Covered Loans | Commercial Real Estate Investor Owned
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	6,375,000		6,600,000
Total	6,375,000		6,600,000
Loans - Ending Balance:
Individually evaluated for Impairment	678,000		6,811,000
Collectively evaluated for impairment	416,099,000		430,877,000
Total	416,777,000		437,688,000
Non-Covered Loans | Construction and Land Development
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	386,000		703,000
Collectively evaluated for impairment	1,601,000		1,433,000
Total	1,987,000		2,136,000
Loans - Ending Balance:
Individually evaluated for Impairment	7,729,000		9,484,000
Collectively evaluated for impairment	114,140,000		107,548,000
Total	121,869,000		117,032,000
Non-Covered Loans | Residential Real Estate
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	11,000		4,000
Collectively evaluated for impairment	2,065,000		2,015,000
Total	2,076,000		2,019,000
Loans - Ending Balance:
Individually evaluated for Impairment	430,000		559,000
Collectively evaluated for impairment	159,765,000		157,968,000
Total	160,195,000		158,527,000
Non-Covered Loans | Consumer & Other
Allowance for Loan Losses - Ending Balance:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	252,000		192,000
Total	252,000		192,000
Loans - Ending Balance:
Individually evaluated for Impairment	0		0
Collectively evaluated for impairment	47,479,000		40,859,000
Total	46,302,000		39,838,000
Total	$ 47,479,000		$ 40,859,000