Goodwill and Other Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Core deposit intangibles
Summary of core deposit intangibles and other intangibles
Gross carrying amount	$ 41,831	$ 41,831	$ 47,748
Accumulated amortization	(30,815)	(27,121)	(29,288)
Net book value	11,016	14,710	18,460
Amortization during the period	3,695	3,750	4,123
Other Intangibles
Summary of core deposit intangibles and other intangibles
Gross carrying amount	19,283	20,433	20,433
Accumulated amortization	(10,877)	(11,008)	(9,839)
Net book value	8,406	9,425	10,594
Amortization during the period	$ 1,019	$ 1,169	$ 1,420