Goodwill and Other Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of core deposit intangibles and other intangibles
Amortization of other intangible assets	$ 4,195	$ 4,714	$ 4,919
Core Deposits Member
Summary of core deposit intangibles and other intangibles
Gross carrying amount	41,831	41,831	41,831
Accumulated amortization	(34,044)	(30,815)	(27,121)
Net book value	7,787	11,016	14,710
Amortization of other intangible assets	3,229	3,695	3,750
Other Intangible Assets [Member]
Summary of core deposit intangibles and other intangibles
Gross carrying amount	19,283	19,283	20,433
Accumulated amortization	(11,843)	(10,877)	(11,008)
Net book value	7,440	8,406	9,425
Amortization of other intangible assets	$ 966	$ 1,019	$ 1,169