Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement of Other Comprehensive Income [Abstract]
Increase in estimated fair value of investment in debt securities, tax			$ (187)
Unrecognized actuarial loss and prior service cost, income taxes	693	895	925	1,135
Income tax on cash flow hedge activity	$ 65	$ 8	$ 161	$ 47