Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Tax expense (benefit) on net unrealized gains (losses) on investment securities available-for-sale	$ 505	$ 10	$ 140
Tax expense on adjustment for pension and other postretirement benefits	$ 3,623	$ 6,051	$ 928