Securities (Details 4) (USD $)			3 Months Ended
	Mar. 31, 2013 item	Dec. 31, 2012	Mar. 31, 2012 PreTSLs item
Securities
Number of PreTSLs having realized cumulative OTTI losses and unrealized losses			4
Amortized Cost			$ 10,500,000
Fair Value	215,855,000		4,000,000
Rollforward of Cumulative Credit Loss
Balance at the beginning of the period			8,619,000
Balance at the end of the period			8,619,000
FHLB and FRB stock
Investments in FHLB and FRB stock	6,400,000	7,300,000
FRB stock included in Other Assets	$ 1,300,000	$ 1,300,000
Number of indicators for impairment of investments in FHLB and FRB stock	0