Condensed Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Tax expense recognized on the amortization of prior service cost	$ (6)	$ (6)	$ (18)	$ (18)
Tax expense recognized on the net gain (loss)	27	43	80	124
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	$ (18)		$ (19)