Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Statement of Other Comprehensive Income [Abstract]
Decrease in estimated fair value of investment in debt securities, tax	$ 0		$ (1,126)
Unrecognized actuarial loss and prior service cost, income taxes	209	121	1,343	(290)
Income tax on cash flow hedge activity	$ 25	$ (61)	$ 71	$ (48)