Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]
Unrealized gains (losses) on securities, Arising during the period tax expense	$ (10,121)	$ 2,760	$ 1,467
Unrealized gains (losses) on securities, Reclassification adjustment for gains included in net income, tax expense	269	216	1,257
Unrealized losses on derivative instruments, tax benefit	3,454	92
Unrealized losses associated with pension and post retirement benefit, tax benefit	$ 8,083	$ (3,031)	$ (6,358)