Credit Quality (Schedule Of Age Analysis Of Its Past Due Loans, Segregated By Class Of Loans) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-89 Days Past Due	$ 109,640	$ 100,874
Loans, 90 Days or more Past Due	90,002	77,599
Loans, Total Past Due	199,642	178,473
Loans, Current	6,318,138	6,055,807
Total gross loans	6,517,780	6,234,280
Loans, Recorded Investment >90 Days & Accruing	18,068	16,179
Owner-Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-89 Days Past Due	11,122	4,625
Loans, 90 Days or more Past Due	16,691	4,707
Loans, Total Past Due	27,813	9,332
Loans, Current	701,093	734,170
Total gross loans	728,906	743,502
Loans, Recorded Investment >90 Days & Accruing	4,038	1,597
Nonowner-Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-89 Days Past Due	12,793	16,694
Loans, 90 Days or more Past Due	11,643	13,285
Loans, Total Past Due	24,436	29,979
Loans, Current	1,715,984	1,523,280
Total gross loans	1,740,420	1,553,259
Loans, Recorded Investment >90 Days & Accruing	2,549	2,233
Other Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-89 Days Past Due	8,379	7,131
Loans, 90 Days or more Past Due	20,808	14,153
Loans, Total Past Due	29,187	21,284
Loans, Current	1,347,896	1,190,921
Total gross loans	1,377,083	1,212,205
Loans, Recorded Investment >90 Days & Accruing	1,687	761
Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-89 Days Past Due	54,168	52,654
Loans, 90 Days or more Past Due	22,095	26,617
Loans, Total Past Due	76,263	79,271
Loans, Current	1,761,989	1,812,454
Total gross loans	1,838,252	1,891,725
Loans, Recorded Investment >90 Days & Accruing	7,363	8,833
Construction & Land Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-89 Days Past Due	14,046	13,809
Loans, 90 Days or more Past Due	16,918	17,820
Loans, Total Past Due	30,964	31,629
Loans, Current	519,713	518,248
Total gross loans	550,677	549,877
Loans, Recorded Investment >90 Days & Accruing	654	1,840
Bankcard [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-89 Days Past Due	394	222
Loans, 90 Days or more Past Due	164	176
Loans, Total Past Due	558	398
Loans, Current	10,678	11,121
Total gross loans	11,236	11,519
Loans, Recorded Investment >90 Days & Accruing	164	176
Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, 30-89 Days Past Due	8,738	5,739
Loans, 90 Days or more Past Due	1,683	841
Loans, Total Past Due	10,421	6,580
Loans, Current	260,785	265,613
Total gross loans	271,206	272,193
Loans, Recorded Investment >90 Days & Accruing	$ 1,613	$ 739