Mortgage Servicing Rights - Summary of Balance Changes (Details) (USD $) In Thousands, unless otherwise specified				3 Months Ended		9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011		Sep. 30, 2012 Mortgage servicing rights [Member]	Sep. 30, 2011 Mortgage servicing rights [Member]	Sep. 30, 2012 Mortgage servicing rights [Member]	Sep. 30, 2011 Mortgage servicing rights [Member]
Changes in mortgage servicing rights balance
Beginning of period	$ 5,717	$ 4,870	[1]	$ 3,276	$ 2,878	$ 2,739	$ 2,441
Servicing rights capitalized				741	277	1,777	965
Amortization of servicing rights				(463)	(123)	(1,147)	(312)
Changes in valuation				(372)	(672)	(187)	(734)
End of period	5,717	4,870	[1]	3,182	2,360	3,182	2,360
Mortgage loans serviced for others				$ 540,735	$ 377,060	$ 540,735	$ 377,060

[1] Note: The consolidated balance sheet at December 31, 2011 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U. S. generally accepted accounting principles for complete financial statements. Certain amounts have been reclassified to conform to the current-year presentation. See accompanying notes to the unaudited consolidated financial statements.