Business Combinations Narrative (Details) (USD $) In Thousands, unless otherwise specified		0 Months Ended	12 Months Ended			0 Months Ended
	Dec. 31, 2012 community	Sep. 10, 2010 First Bank [Member] branch	Dec. 31, 2010 First Bank [Member]	Sep. 10, 2010 Acquired Book Value [Member] First Bank [Member]	Sep. 10, 2010 Fair Value Adjustments [Member] First Bank [Member]	Sep. 10, 2010 Core Deposits [Member] First Bank [Member]	Sep. 10, 2010 Cash On Hand, Branches [Member] Acquired Book Value [Member] First Bank [Member]
Business Acquisition [Line Items]
Number of bank branches acquired		10
Number of communites offering banking capabilities to customers	25
Acquired deposits		$ 337,429		$ 336,016	$ 1,413
Acquired loans		(133,117)		(135,219)	2,102
Acquired premises and equipment		12,951		5,266	7,685
Deposit premium percentage rate on core deposits acquired		4.77%
Deposit premium on core deposits acquired (in dollars)		15,600
Cash		180,074		180,074	0		1,800
Cash paid to acquire company		178,300
Acquisition related costs			1,154
Acquired core deposit intangible assets		$ 3,050		$ 0	$ 3,050
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						10 years