Goodwill and Intangible Assets (Schedule of Goodwill and Intangible Assets) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Goodwill [Roll Forward]
Total goodwill, beginning of period	$ 118,434	$ 109,639	$ 109,639	$ 95,519
Established through acquisitions	0	0	8,795	14,120
Total goodwill, end of period	118,434	109,639	118,434	109,639
Gross core deposit intangible balance, beginning of period	28,497	26,651	26,651	8,896
Accumulated amortization, beginning of period	(9,894)	(5,874)	(7,955)	(4,032)
Core deposit intangible, net, beginning of period	18,603	20,777	18,696	4,864
Established through acquisitions	3,943	0	5,789	17,755
CDI current period amortization	(1,177)	(1,044)	(3,116)	(2,886)
Total core deposit intangible, end of period	21,369	19,733	21,369	19,733
Total goodwill and intangible assets, end of period	$ 139,803	$ 129,372	$ 139,803	$ 129,372