Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Components of accumulated other comprehensive loss, net of related tax benefit/expense
Net unrealized gains on investment securities – available-for-sale, net of related tax expense of $2,232 at March 31, 2013, $2,301 at December 31, 2012 and $2,265 at March 31, 2012	$ 4,143	$ 4,274	$ 4,208
Pension and other postretirement benefits adjustment, net of related tax benefit of $18,726 at March 31, 2013, $19,058 at December 31, 2012 and $15,249 at March 31, 2012	(34,777)	(35,393)	(28,319)
Accumulated other comprehensive loss	$ (30,634)	$ (31,119)	$ (24,111)