Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Net interest income	$ 39,880	$ 36,812	$ 117,471	$ 112,182
Provision for loan and lease losses	5,149	(502)	7,648	4,852
Total noninterest income	20,718	29,766	72,044	81,432
Total noninterest expense	47,147	47,159	142,660	128,758
INCOME BEFORE INCOME TAXES	8,302	19,921	39,207	60,004
Segment Assets	4,912,730	4,593,197	4,912,730	4,593,197	4,990,553
Average Loans	2,937,508	2,727,806	2,906,970	2,660,556
Community and Other Banking
Segment Reporting Information [Line Items]
Net interest income	39,291	36,412	115,968	110,332
Provision for loan and lease losses	5,149	(502)	7,648	4,852
Total noninterest income	12,309	13,988	37,630	40,902
Total noninterest expense	36,813	35,597	108,877	99,902
INCOME BEFORE INCOME TAXES	9,638	15,305	37,073	46,480
Segment Assets	4,825,781	4,467,574	4,825,781	4,467,574
Average Loans	2,867,933	2,628,811	2,820,418	2,570,493
Retail Mortgage Banking
Segment Reporting Information [Line Items]
Net interest income	589	400	1,503	1,850
Provision for loan and lease losses	0	0	0	0
Total noninterest income	8,409	15,778	34,414	40,530
Total noninterest expense	10,334	11,562	33,783	28,856
INCOME BEFORE INCOME TAXES	(1,336)	4,616	2,134	13,524
Segment Assets	86,949	125,623	86,949	125,623
Average Loans	$ 69,575	$ 98,995	$ 86,552	$ 90,063